Geof. I am not sure of what the correct term to describe this is but im wondering about heat/cold transfer from a metal outer skin to the steel wall studs.

This might not be much of a problem in a trailer but I am considering a motorhome with a lot of winter use.

Even with good insualtion between the studs would there be a transfer of cold between the metal skin and metal studs creating cold spots.

I just used some polyiso for insulating a passive solar heating area on a house. 2 1/2 inches thick. Got some sheets left over from a bigger project. The price was right - free. I would be curious about what method did you use to cut the panels into smaller size to bit between the studs etc?