Just something I've been thinking about. Don't know how feasible, might try to build it one day. A rectangular box, insulated,devided into two sections, a door on each side. One side has a shelf halfway. On the top shelf, a plastic container witha drain hose, draining into a clear container.. jug, bottle, whatever. A block of ice in the top container. As it melts it drains into the bottom container to supply cold water.
The other side can also have a shelf, and this is your food storage side. The middle partition will have a slot cut near the top between the two partitions. O the bottom, a small 12 volt fan to circulate the air from the ice side to the food side, and the warm air pushed into the ice side at the top. As the ice melts you can buy bag ice to replenish the block ice, just make sure you use the water in the lower half.
This would not use a lot of battery and could be run continuously and the food would stay cold, and dry. The purpose of the two doors would be to keep the cold in when using the "fridge". You could also hook it up so that the fan shuts off when you open the storage area.
If anybody has already thoughtof this, well, great minds think alike. I know I haven't seen this anywhere. Also if you want to build it, be my guest, I won't sue you. Just let me know how it works....