Food Cart Hood Installation

Hi all,
 
I've been a lurker for quite some time.  I've been thinking about posting but I kept procrastinating and never posted until today.
 
I have been building a food cart for months...my wife wanted a food cart so I decided to take advantage of the situation and turned it into an opportunity to learn something new.  Looking back how it's been,  it wasn't a very wise decision but I learned how to weld and build a trailer from scratch.
Anyway, I'd say it's about 80% finished and I'm almost ready to install a range hood.   I already have a commercial hood but I am wondering how I go about installing it.
 
In city of Portland, only health department cares about how you install the hood so far.  Even the health department does not seem particularly picky about it since they still allow non-commercial range hoods to be installed on food carts.  So, technically I can most likely pass their inspection if it looks and works just fine.
But since they might make commercial hoods mandatory and change their installation requirement for hood in the future, I want to make my installation future-proof and make my food cart operable out-of-state (just in case).
 
Some states I believe have more strict requirements for hood installation.  If anyone is familiar with such requirements, I'd like to know.  Do they typically go by NFPA 96?  I'm mainly concerned about clearance requirement for duct and hood, and when you use fire barrier insulation, the required thickness.  Thanks!

In my neck of the woods hood requirements vary according to what and how you are cooking. I have about a 5' hood for ventilation...no fire suppression. The local authorities are fine with that, but a chargrill or deep fryer would change things. I believe the Fire Marshall would get involved at that point, but not sure.
 
Also, I would think that if the requirements change in the future, you would be Grandfathered in...course, I have been wrong about a lot of things and know nothing about your local situation.

Hi,  definitely check with the fire marshal, they inspect all hoods - fixed locations, mobile, whatever. Anything else, including 'approval' by the health department may not be legal now or in the future! DON'T TRUST the health department on this one.
State and even county or city ordinance will dictate whether you need suppression or not. Here in Alaska we need a commercial hood, at least 6" wider than the cooking unit, and some kind of built-in grease trap. Even with fryers and grills, so far in my area we don't need suppression, but I've heard htey do oever in Anchorage.
 
A couple years ago we looked into setting up a mobile rig in Coos Bay area, and I think down there they wanted suppression with any kind of frying or grill.

Thanks for your inputs.
I think Relentless is right about old food carts get grandfathered in when new rules enact.  Only exception to that is when you change the ownership of the food cart, maybe?
Anyway, I decided to get some fire barrier duct wrap and put it around the duct, and between the ceiling and the hood to make it a little more fire proof.  It isn't cheap so I wanted to avoid it at first but considering that it is much easier to put it now than later, I decided to get it now. 
Fire suppression system would be nice but it is expensive and also I'm too far into construction to change my mind so I'm skipping it this time around.
Here in Portland, the Fire Department is not very picky against mobile kitchens so far.  When applying for a fire permit, they get you a piece of paper with rules pertaining to the use of gas and cooking equipments written on it.....you read it, sign it and pay $25 per year for a fire permit.  It is expected to change soon due to increasing number of food carts (over 600 food carts here in Portland) but that's how it is now.