I would think that a well insulated fridge would keep cool for quite a while.
I have a 2 way (110V - LP) in my camper that works well. I haven't had any problems with it so far. We use it differently than our home unit. We pre-cool everything before we put it in for the trip.
If I have to replace it, I'll put the same back because I don't want the weight of the batteries that would be required in a camper trailer.
In our first camper, we put in a 3 way(12V 110V LP) & won't bother with that 12V option ever again because the 12V amp draw was enough to quickly drain the batteries if you ran out of LP. When that happened, we had no lights & couldn't even cook the meat before it spoiled (primitive park with no outside fires- we didn't take a grill because we had the LP stove & didn't have room).
For my bus, I'll probably use a 110v fridge that is the 'old style' that isn't frost free & doesn't use a fan. (The defroster eats a lot of electricity.)
I'll minimize its electricity needs by :
- disabling the heat strips around the door. (they are there to minimize condensation collecting there.)
- getting one that had the condenser coils on the back - they can be spaced further away from the box & more insulation can be installed to keep that heat away from the fridge.
- adding more insulation to the sides & door so it keeps cool longer.
- ducting an efficient as possible draft behind the fridge around the condenser coils to increase the efficiency of the fridge.
- modifying the setpoints on the thermostat so the compressor runs longer & starts less frequently.
- following Gary's lead with the dedicated inverter.
All these modifications will be something I can do that will give me the performance of a super high efficiency unit for less $$$. Since I'm building the bus interior, this will be included in the plan.