David and Bob,
We are having an unusual cold snap here in the Portland OR area, and I woke up to 21 degrees this AM. My coach is parked outside here at my house and not yet inside out of the weather (want to build a storage building, but need to work out the location/grading/slab work and of course money issues first.)
Like others, I also use an oil filled heater in the coach to keep it warm when parked. I converted an unused welder outlet in the shop to a 50 amp RV service, so no worries about which circuits are active on shore power. In additiion to the heater (located in front of the range door just like David...) I have a small ac fan on the desk that is set on low speed -- very quiet and not much power used. I don't use the roof AC units to circulate air in the unoccupied unit.
I also have two ceramic heaters in the storage area set to low (750 watts each) which are powered from the 20 amp outlet for the basement freezer. I did have to run a power cord through to that compartment, but by taking out the round vent grills and then notching the plywood out past their flanges, it was a simple matter to snake a heavy duty extension cord from the freezer bay into the main storage. Since the ceramic heaters each have a fan, the air is well circulated, and I have a remote temp sensor in there that registers at the dining area where the 'base' unit reads the temperature and humidity of the coach itself. Even at 21 degrees outside this morning and being that cold or colder overnight, the basement was at about 56 degrees. So far I feel safe without having done any draining of the water system, but appreciate hearing the greater knowledge of the forum on that issue... This is my first coach and my first winter with it
My smaller travel trailer was alway safely inside the shop, but at 20 ft long and under 10 ft tall it is not as much a challenge to house as the Tour Master...
Chuck