On Kijiji, I quickly found a 24" x 24" x 24" Danby 120 Volt bar fridge that was built in the 80's. My daughter and I took a look at it and found that it was a bit dented, but otherwise in perfect working order. These little fridges have a 'floating compressor' which makes them ideal for withstanding the bumps and jars while driving on trails. After paying only $20 for the little fridge, we then drove to Home Depot where I bought one sheet of 1/2" pink high-density foam, white silicon caulking and a roll of white Mactac®. $20 dollars in supplies later, we headed home for our experiment.
This project cost under $40, so it would be easy to toss this fridge to the recycling curb if it did not work. With this in mind, I was very surprised on our first trip with this little fridge when it ran like a top. It worked so well in fact, that we never set the temperature gauge to over three or it would freeze our food. We can run the fridge for three to four days, depending on outside temperature, on two 12 Volt batteries without charging them. Adding a solar panel to the truck would make this even more efficient. This little fridge was only supposed to keep us going for one summer, but we are now into our third year. The money saved by not purchasing a conventional 12 Volt fridge/freezer unit has been wisely invested in other gear. I would love to upgrade from this fridge one day, but for now we see no reason whatsoever to do so.
This fridge will not win any slick or cool gear awards. Instead, this solution might be useful for someone who is just starting to get equipped for overland travel or for those with a small budget. Saving some money here has certainly helped us to gear up with other things!