We used an Igloo thermoelectric cooler on our recent trip. It worked great. We usually premake a few things and freeze them before leaving (lasagna, all our meats....) so the TM fridge and the Igloo have something already cool in them. (we drove for two days before cooking)
My only concern was the AC adaptor got really warm, so, while we were camping, we put the cooler outside under the front bed on a grooming table. We needed two plug adaptors to be able to plug the AC adaptor in (left my power strip home) because it is a chunky transformer. The cooler worked great -- my friend only unplugged one adaptor so when the shells were raised my plug cover was torn off.
