Tammy,
Your temps surely are lower than what we experienced when we winter camped in Gaylord, Michigan, many moons ago. We had a TT, nothing enlosing the bottom of the trailer, cold cold cold cold. TT not what we consider to be state of the art for 2008, as it was built in 1989. I think we probably were in residence during temps down to 10 or so??? Yea, above 0. It has been long enough that I have blocked that info from my gray matter, we could have been to 0 and I would not remember! SNICKER.
ANYWAYYYY, I do not recall ever having the trouble you are having. We did run on our 30 pound tanks for a few days, but switched to a 100 pounder pretty quick.
That said, the furnace always ran just fine. The microwave was another matter, when we would arrive in camp, it was so cold that it would not run until the rig was warmed up over 40 or so.
Do let us know how this progresses. Very interesting situation.