This is a popup that did not come with a fridge. I have not completely worked out the ventilation yet but I would not run the fridge on LP with the popup down and in tow.
The 12v element draws ten amps so running it off the 7=pin should not be a problem.
I think the reason 3-ways are out of vogue is the same reason new RVs come with televisions on the outside- because it's no longer about camping. And I'm sure they had trouble educationg people on the limitations.
Of course it won't cool properly on 12v. That's about 300 btus and it needs three times that to work properly.
But, if i take off with it cold and loaded I'm pretty sure the 12V element will minimize the loss over 10 hours of driving.
