6x8? Stand on a sheet of plywood and try serving,You'll wish for bigger.You can buy a good used already outfitted trailer for 3-10k.
with almost any trailer you need a 3bay sink a handwash sink,storage and hood with maybe ansel.and put all that on a piece of plywood. JM2C
Oddly enough I built a cart a while ago from a trailer a guy brought me, was about 6' by 9' with 6' ceiling height. Thanks to it being a Portland OR build I was able to get away with a lot of stuff but in the end it had:
Rear and side service windows
Mini 4 burner range with oven
Commercial single door prep top fridge
Large toaster oven
10CF domestic fridge/freezer
Single basket counter top fryer
Small 3 comp sink
Separate hand sink
36" domestic grade hood fan
Enough room to prep and serve a full menu (he had about 12 items)
2 people worked comfortably in it
Just sayin, with the right person designing the cart, anything is possible.