Time for a little break in this serious discussion -- our first trailer had almost no insulation. Went to Yellowstone in October. Temp one night dropped to 15. Temp in the trailer was below freezing. Of course the pipes froze (but later thawed).
But the most fun was the coffee maker -- did you know that a power cord can freeze? Here is proof:
Click For Full-Size Image.
This photo is not a trick photo -- we took the coffee maker out of the closet and the cord was frozen.
We did just fine, by the way -- did not run the heater at night -- slept under a down comforter and two blankets and slept very well!