I think in that situation, I'd acquire a quiet generator and mount it on a trailer hitch, and then plug in at night. I might even explore the dry ice methods of keeping things frozen.

I dislike relying on inverters running on battery power. Despite their size weight and bulk, batteries just do not store very much energy. They are also fickle female dogs when they are abused, and when I say abused I mean over discharged and not promptly and fully recharged.

 

I'll second that thought (generator) for a couple of reasons.

Small generators are very inexpensive today and I'm sure it'll be cheaper than buying a bank of batteries + HO alternator + 0 gauge wire, connectors, battery boxes etc. My 3200 (4000 watt peak) generator cost about $370 delivered.

I've read several posts that claim some AC/DC power inverters can disrupt the PCM on these Dodge trucks/vans. Probably has something to do with the modified sine wave they create feeds back and interferes with the computer. Could even be due to all the unshielded sensor wiring but I'm just guessing.

All of the food trucks I've seen here in SA use small generators, most often they are mounted on a trailer hitch cargo carrier tray.