Mine is 2 pane with the second actually screwed to the inside of the camper.
In the 20 degree weather we have had I ran just the pluming and bedroom heater and it did very well. It did cycle at 1 hr intervals although the complete living area was removed and the slide seals removed . So I was pleased and cant wait to see what the finish result will be. From the construction standpoint I have to say this is actually kind of fun to repair. It is much like a regular house with the exception of dimensional wood. My biggest concern is of course longevity and comfort added with noise control. Have you ever slept in a cheap camper and the bed slideout is like a noise catcher?
And it really isnt hard to repair.