Ran into this while snooping around the Internet for something else
http://www.roadgiant.com/roadprorpsl-35012-volt15quartslowcooker.aspx
It caught my attention because some time back there was some discussion on
using a small 110v AC crock pot, w/inverter, while driving and then having a
hot dinner waiting when you stopped at night.
this just might do the job.  If I were using it I'd only use it while
driving, it's going to suck a lot of juice if the engine is off.
That site has several other such 12v cooking appliances.