Many if not most thermoelectric coolers will also have a warming mode to keep food warm. They are not really meant to bring food up to servicng temperature, they are more for keeping warm food warm.
A visit to a truck stop will show you quite a selection of 12 volt appliances that are meant to cook food. I would use camping gear myself, but the open flames must be used outdoors.
Truck stop! Of course! Great idea!
Thank you both for your responses. ^^