Advice from seasoned pros?

I am the business manager for a Christian school.  We have been looking for innovative ways to supplement our school's income and a decision was made to own and operate a concession trailer during the summer season (May - September) at area festivals and fairs.  We will be hiring someone to manage the truck but until that person is hired and on board, it has fallen to me to get the trailer "off the ground."  I do have two other members on the committee but since I am at the school full-time, the majority of the work has become mine.  I apologize for the length of this post, but I want to include sufficient information about our plans so it is easier to answer my (many) questions.
We have determined that our menu will include a baked potato bar (a limited test of this was recently done with a local area food trailer that one of the committee members is associated with an it went over very well), hot dogs (with some of the same toppings used for the potatoes), as well as blended iced coffee (and other flavors) drinks.  We are debating about also selling gourmet popcorn.  I am trying to design the trailer so that we can add to or change the menu later if we need/decide to.  The trailer we are having built (still in design phase) is 8' x 18' with the ability to serve either out the passenger side (12' of windows) or the back (6' window).   Equipment that is planned to be purchased with this is a 2-door upright refrigerator, 1-door upright freezer, 1/2-size convection oven, 53" counter-top refrigerated prep station for toppings, and a food warmer (2 hot wells).  At this time we have not purchased a grill or fryers but have left the option open as we are installing a hood system over the area that these items would be if we decided to install them.  For the time being, this will be work space with a stainless steel work table.
To have the new trailer built, we have been given bids totaling about $54,000 for the turn-key trailer.  We had been hoping to keep the initial cost to about $40,000.  Are we being unrealistic with our cost estimate?
Questions that I have (so far) include:
1.  What kind of point of sale system has worked best for you?  What would you recommend?  Has anyone used the NCR Silver POS system?
2.  As we will be travelling several hours to many (most) of our venues, what are your recommendations for keeping food cold/ice frozen during the trip?  The builder has suggested a 6500 watt LP gas generator that would be run during transport and could also be used to provide power for the trailer at events that do not provide electrical service.  My concern is the cost of the generator ($6,700), LP gas, tanks, rack, regulator, set-up and testing would add $9,600 to the cost of our build.  
3.  Suggestions on best way to hold hot baked potatoes?
4.  Thoughts on the proposed menu?
Any advice and comment is very much appreciated.

First off, I think you can do better than $54,000, and is that including the $9,600 for the generator? I also think you can do far better on this.
Does this price include a fire suppression system? If not, add $3-4,000 This is something that you will want/need if you plan on using any appliance past an oven.
It may/not be required in your town but will be in another, limiting where you can work.
I'm interested in why you would want a 12' serving window?
A counter top oven is going to limit your capacity to produce your key menu item, baked potatoes.
If I remember correctly(been a few years since I made bakers in a restaurant) you can place approx 30, 90ct potatoes on a full sized sheet pan, so a counter top oven is only going to allow 2 maybe 3 half sheet pans (30-45) at a time.
A full size oven will allow 3 full sheet pans allowing you to cook 90 spuds at a time, with a cooking time of approx one hr.
You can buy a 36" flat top grill over oven and have that in one place under the hood, freeing up counter space.
A warming drawer will hot hold potatoes for a short time, it is best to serve them within 30 min or so, the flesh will turn from fluffy & white to pasty and will start to turn brown on you, no one wants an old potato.
Hot dogs????? Everyone does dogs, you might not be able to serve them some places, or have five other vendors selling them also.
Are you going to be staffed with skilled cooks, or just worker bees? If you have skilled cooks, then I would look at expanding your menu beyond potatoes.
Have you thought about char grilled burgers & hand cut fries? I'm talking a fully dressed burger, not just a frozen patty on a crappy bun with some mayo smeared on it.
You can get $6 all day for a 1/4lb cheese burger and another $3 for an order of hand cut fries, that's $9 a wack, vs???? (how much are you proposing for a potato)... I wouldn't pay more than $5 and would rather see it for less.
That $9 burger and fries cost me $1.90 to produce with a $7.10 profit, how much profit will you have on a baked potato?
Fresh lemonade shake ups do well, and have a high profit margin, there are several threads on here about fresh lemonade.
I wouldn't waste a bunch of money on a pos system, you can buy a nice cash register that will give you all the reports you will need for under $300
I would like to see a layout of the trailer you have been given bids on, along with what you get for your $$
Also, what will you pull the trailer with?
More later.
 

Chefbuba, thank you for taking the time to respond.  The $54,000 does include the $9,600 for the generator and related equipment.  It also includes a 6' hood system with "fire protection ansul and fire panel behind cooking' ($4,200). The 12' window won't all be open for serving.  It is actually two 6' window sets.  We would be serving out of the rear 6'.  The other 6' was more for letting in light/ventilation and letting customers view the counter either as we are making their food (ala Subway) or to display product (gourmet popcorn).  As for the oven, the person we are working with had the experience of a health inspector asking him how he was cleaning full-size sheet pans in the small sinks and he recommended the 1/2 oven for the sheet pan size.  I, too, had concerns about being able to cook enough potatoes in a 1/2 size oven at a time to keep up with demand.  The obvious answer I now see is use a full-size oven with 1/2 size sheet pans.  However, a full-size oven is going to add even more cost.  Guess we need to look closer at a cost-benefit analysis for the half vs full size oven.  The hot dogs were thought of as an easy way to expand out menu because we could use some of the same toppings for the potatoes on the dogs (chili, cheese, onions, etc.).  As for staffing, we plan to hire a manager to be in charge of the trailer, but it would mostly be staffed by volunteers from our school.  There may be a few that will help at more than one event, but we need to keep the menu simple enough that first time volunteers can be quickly brought up to speed on preparation of menu items.  We are well aware of our inexperience and thus have scaled back our initial menu offerings until we have at least one season under our belts.  We went with the baked potato bar because it is not something you typically see in our area. We had done a survey with our student body and staff of food items they'd like to see us do and have available are area events and the baked potato bar was by far the leading item they asked for.   Burgers and fries/pork sandwiches/BBQ/indian tacos are all over the place as are the fresh/frozen lemonades.  We were trying to find something somewhat unique for this area that would set us apart a bit, hence, the baked potato bar and blended coffee drinks.  The profit margin on the potatoes is pretty good.  When the test run was done recently, it cost approximately 50 cents per potato to make and they were selling them for $3.00.  They only had 100 lbs. of potatoes and they sold out of them within an hour or two (this was a swim meet).  At our local fairs and festivals you cannot buy a meal for under $6.00 so I don't think we'd have any trouble selling them for $4.00 or $5.00 and still be less expensive than less healthy options.  As for a POS, I, too, was leaning toward a cash register verses and ipad based system.  Here in SD internet service may or may not be available for any given venue.   The funds to get this venture started are being donated to the school so I feel a responsibility to make sure they school is getting their money's worth and will see a good return on the investment.  This is something we plan to do each summer for the foreseeable future to supplement our income and the school board wanted to "do it right" from the start.  Used verses new trailer and equipment had been discussed and the decision was made at the board level to go with new so we had the warranties on the trailer and equipment (in part because of our limited experience in being able to service/maintain/update a used trailer and/or equipment).  I will try to PM you with a drawing of our proposed layout and additional detail about the trailer and equipment bids.  I appreciate your willingness to share your experience with me.

Chefbuba, guess I can't PM you until I've been a member for a couple weeks.  Bid for the 18' trailer (w/ AC, coin rubber flooring, 12" addl height (7' ceiling), nice 2-tone paint job) came in at approx. $16,000.  Interior and equipment came in about $38,500 and includes the hood system w/ fire protection (I realize we don't need it for our present equipment set-up but wanted it installed in the event we later decide to add a grill/fryers to expand our menu selection), 3-sink wash station with drainboards plus sink for hand washing including potable and grey water tanks, heater, pump, power panel (208 volt 50amp), stainless work table and front counters, 1/2 size convection oven (this may change based on our earlier comments), 2-door upright refrigerator, 1-door upright freezer, Nemco Food Warmer (two 12 x 20 hot wells), SilverKing 53" topping rail (countertop prep station for cold toppings), wall shelving, 6500 watt LP gas generator including tanks and related equipment and testing, and installation and test of all equipment.

Hope that is a REALLY nice trailer. My record was 18k for a build I sent to Canada. Was a 12X7 cargo trailer retrofit, new trailer with 7' ceilings, stainless/FRP walls, commercial vinyl flooring, 3 service windows, commercial 4 foot ventilation system, new 4ft prep top fridge, new 2 basket LP fryer, new griddle top range with lower broiler, 3 comp sink, hand sink.
 
That was turn key ready to go....
 
Maybe my prices are to low lol.

I wasn't going to reply in this thread but it nagged at me until I came back to it. I think it would be best if you thought about some things in more depth:
 
--The price of potatoes has very little to do with your net profit. If you're taking the trailer out two days a week (Friday and Saturday?) you are either going to be throwing away a good bit of food Saturday night, or you are going to be serving six day old food next weekend which is unwise if not downright dangerous. You will not be able to accurately predict how much food to buy for any given gig, that is a fact of life in this business, so you buy too much and hope for the best. I don't mean the potatoes, I mean the sour cream and butter and bacon. Make sure your assumptions re food costs are reasonable, make sure they include waste.
 
--Many venues are going to require you to carry a 1MM liability policy. You will also have to insure the trailer & you will need to insure the tow vehicle (if a student's Dad is pulling your rig with his pickup truck or whatever, his auto insurance will not cover you OR him if he wipes out). You will also be required to carry worker's compensation for some events. It does not matter if the workers are volunteers. Price this before you proceed. In most areas it will be 350-ish per month. Way over a hundred potatoes. You may spend one weekend out of four just paying for insurance.
 
--Fuel for the generator, fuel for the tow vehicle, propane maybe. If you intend to run the entire trailer off a gasoline-powered generator you may be amazed at what you spend on fuel.
 
--You need to get an accurate assessment of your electrical needs and size your generator to it. If you don't know whether you are going to be running commercial grade coffee makers and so forth then you don't know how much genset capacity to pay for. Too little capacity and you're popping breakers and turning some things off so other things can warm up. Too much capacity and you're wasting fuel every minute you run the thing. Do not build the concession and then decide what you're going to sell. Decide what you're going to sell first, otherwise you can't plan.
 
--Many (probably most) full time food concessions can not even support two adults. If you are only deploying 8 times a month or so, paying a manager to make sure the logistics get done right may be prohibitive. It is not the time you spend vending; it is the bookings, sourcing, shopping, food prep, dealing with taxes and government, etc. Don't be surprised if your manager spends three hours on his job for every hour he is in the trailer with the serving window open. Can you afford that?
 
I don't mean to be abrasive, these are just some considerations I thought of, and I do hope this works out very well for you. =^)
 
Ken

@TamaleTrolley, thank you for your candor.  This is why I posted the original message...because I am certain there are things we have not taken into consideration.  It helps when I approach the board to have comments from those that do this for a living rather than my own suppositions.  The more I've delved into this, the more concerns come to mind.  You have definitely given us some things to consider.  

I have been watching this thread and it interests me a lot. On several occasions I have started to post something, then back away cause what I have to say is very negative about your situation. From your first post, heres my thoughts:
You work for a Christian school that has very deep pockets. Nice to be able to spend the amount of money you plan on a trailer plus hire a manager to run the trailer. You plan to work the trailer approx. 5 months out of the year. Personnally, I don`t think this will allow your school to raise much revenue. You also mentioned there are 2 other people to help you, but since your at the school most of the time, most of the work has fallen on your shoulders. Seems to me you better get used to this. You also mentioned "I am trying to design the trailer" , once again, your not getting much help. You asked about a POS system. OK, silly me to even think like this, your a Christian school, I assume Christian members will be manning your trailer, then why a POS system needed right now? Get a cigar box. lol You talk about power issues, been doing this for 13 years. 99.9% of events I go to have power. This is something that is asked before submitting payment to the event organizer. Maybe rent generator if needed. Also, ask if water and ice is available. In 13 years, I`ve seen about everything baked, cooked, fried. Only once can I remember a bake potato set-up. Everybody does hot dogs. Kettle corn down here does great. Have you booked any events yet? If not, NOW, and I mean NOW is the time to be getting applications. Most events are already booked up. Also, mom and pop concessionaires despise non-profits. Some wouldn`t give you the time of day. Your volunteers are going to get tired working weekends. Oh, they`ll have fun a time or two, but I bet they`ll find an excuss to be busy the weekend you need them the most. This business is not for pussies. Instead of trailer first year, why not go to Sams and get you a $200 E-Z Up, a few tables, make some signs, etc. and see how things go from there. If you do persue the trailer idea, hope we don`t see it on E-Bay next year. Sorry to be harse, just my thoughts and memories of people and organizations that have done what your partaking.
Good luck.

I totally agree on the latter of the previous post^.
OP has A TON to learn (and do) in a very short amount of time. Which is why setting it up smalltime is the way to go instead of them throwing you in with the sharks! The food truck industry is brutal, fierce and did I mention brutal? The above poster and I aren't trying to scare you but this is just too much to do in a very short amount of time especially for someone who is totally clueless about this industry. Best thing to do is switch gears and do it on a smaller scale and you will see your ROI a lot quicker. To get an idea on what to sell, go to gmpopcorn dot com. I wish you the best of luck!