There's 40+ replies here so if I'm duplicating...
What about a compressor powered portable?
A small one uses about 6 ah a day, with modern small compressor and a small .7 or so cf box.
No tearing things up. No gasp-worthy mistakes. No installation at all. Just plug it in to 12v CLA or wire a 12v line. Or, use a 110v to 12v CLA converter on shorepower.
For cruising, fill up the ice box with ice and food, and when the ice has fully melted 4 days later, transfer remaining food to the fridge.
A .7cf fridge is small enough to stow, but holds a respectable amount of food. Especially with no ice in there.
Plastic containers come in handy, and can be bought in sizes that match the fridge dimensions.
And we're only talking about $400.
Also you can use it in your car etc.
http://www.defender.com/product.jsp?path=-1|2276204|2276226|2276228&id=2423633