I really appreciate all of your thoughts. Remember, I'm only in the information collecting stages right now. Only pictures that I might be able to provide are maybe of some dead brain grey matter.
Madjack, I agree that the thermoelectrics are not efficient enough. They would drain too much battery and provide cool only ambient temp -40 Deg. I suppose that were it 90 deg out and you handed me a 50 deg beer that had been sitting in a thermoelectric for three days, I'd drink it. I'd politely pass on the burgers you just made, though. George, many campers here south of the border use 3-ways, however, I would opt for a two way. Don't think 12V is worth the $$$.
My reference to a chimney is more in line with the airshaft thing. The fridge would face to the rear just like any other fridge would. Directly in back of the fridge there would be a 2 or 3 inch X 22 inch(or whatever the width of the fridge is) hole in the floor. There would be a corresponding hole in the roof of the tear. I would use sheet metal to make a duct (2 or 3 inch X 22 inch) that would run floor to ceiling. Put a vent at the floor to let cool air in, a vent on top to let hot air out, and a cap up top to weather proof it all. Probably some screening top and bottom to keep out the bees.
All this thinking is making my head hurt. I couldn't stop thinking about this last nite. Kept me up most of the nite. I want to do this, BUT, if it doesn't work, it'll cost big bucks.
I'll try to get a drawing down on paper and maybe that'll help to actually show you what I mean. I'd give up a sink and 5 gal water supply and a microwave to make up for the difference in weight. Couldn't use a microwave without electricity anyway.
Stan