The Pelt device is inefficient, did you check that out by chance? They consume a lot of power for not much cold, and to get them cold enough too cool a volume space will be a LOT of power.

However with the efficiency of the newer conventional fridges, and the efficiency of current inverters... it *may* be more better to look at that route.

Lastly, a propane/12vdc/120vac fridge such as is found in an arrr veee may be best suited, on LPG a 20lb tank should like a good long while.

Let google be your friend.

EB