You will need a dual battery system and a means of charging it if you are not driving if you want to run an Engel/Waeco type of fridge for a couple of days so that the starting battery is not drained.

garry 07MY RRS TDV6
Arctic Frost
Aspen Interior

Think most fridges have lids, not doors.

We have a dometic which technically isn't a fridge, it only cools to a temp below ambient, so near 0c at 20c, more like 20c if you're in the desert and the outside temp is 40c. For use in the UK, except in the hottest of days in the summer it's been just fine for us, we only ever take a couple day's worth of food with us anyway, there usually are supermarkets near our "expedition" trails

It can be powered with 240v (great drinks fridge at home), 12v in the car or gas when in the tent, much much cheaper than a proper fridge, more space inside, but clearly not as good at keeping things fridge-cold. 

"Roads ? Where we're going there are no roads." Back to the future.