As others have talked about, worry about the low temps.
Remember, a problem in those temps is no longer "just an inconvenience", it can quickly turn into matter of life and death.
Problems to expect:
Low battery capacity because of cold. maybe heat for one night on two 27 series batteries?
no solar charging
generators will not start.
moisture in propane tank can freeze and block lines (I had this happen in 25 deg with a 6mo with us. it was not fun.
propane might not convert from liquid to vapor and prevent heater from working
