I've got the Road Pro lunchbox oven. It uses foil liners so clean up is just throwing away the liner.
Most truck stops stock the liners, as do many Wal-Mart's. They cost twice as much at truck stops.
I have also used the Burton unit with adjustable temp, but it burned up 12V plugs like crazy (no matter the setting).
The Coleman cooler is probably the best 12V cooler out there.
Eventually the fan will quit, but it is easily replaced with a standard computer case fan. The size it comes with is 92mm, which is impossible to find. An 80mm fan (easy to find) will do in the cooler months but you're much better off with something larger.
I found a CPU fan/heat sink combo unit (for $15 at a little computer shop) that works even better than the original. The fan is 112mm in a round housing. It's a vey tight fit, but it fits perfectly. That is the largest fan that will fit.
I just dismounted the fan and connected the red and black wires.
It keeps things at about 35-40 degrees during very hot weather.
I might need to splice in a fan speed control knob when the cool weather hits so things don't freeze.