I installed a 12V outlet in the bed of my truck and am drawing the power from the camper charge line. It will only operate when the truck is running (which I like and don't like) so it's really only used on long trips. When I get to the CG, I have a 12V power supply similar to this one
which provides more than enough power to run the cooler. You are right though, it does draw a lot of amps.