I started this thread and want to say thanks to everyone who has jumped in. I am living in my motorhome, my Solera 24W, right now. The temps are in the lower 30's at night but with my electric heater going its fine and very comfortable...70ish degrees. As it gets colder and I keep living in my box, I will post here and share the experience. Oh, and I did buy a bunch of the spray foam from Home Depot and very thoroughly coated all the hoses including the sewer pipe and any other water or waste related thing under there. It was easy since that stuff sticks to whatever you spray it on so working upside down was no problem. At night I draw the shades but have not yet done anything else to the windows. In Bend, Oregon the humidity is usually around 30% so condensation is not as problematic as in many other places.
I used to live on a boat in Seattle and it was the circulation of air that prevented condensation in that very wet environment.
2015 Solera 24W
Three big dogs
Two kayaks, One SUP