I will start out. We are wintering full-time at 7000' at the KOA in Flagstaff, AZ. It is 36* right now, cold rain, 2-6" of snow forecast before the morning. DW took a great job in the cardiac unit at the local hospital so we will be here for a while, taking a break from our travel plans. A couple snow storms so far (10-12" from the last one), usually in the low 20s at night but several single digit nights.
We have a '04 Newmar Mountain Aire 4016, 400ISL, three slides. Great insulation, heated basement, dual pane windows, traditional propane furnace, two roof AC/heat pumps.
The things that have worked for us are:
1) The big deal we did was to have a local propane company bring out a 100# propane tank and connect it to the coach. At night we set the furnace thermostat to 57* and are very comfortable sleeping and the tank is only down to about 67% after nearly two months. This overnight setting in the coach keeps the vented water bay in the low to mid 60* range even when it is cold outside (small volume to heat so it warms up more than upstairs), the rest of the basement stays in the upper 50s. When the furnace runs, the water bay gets up in the 90's. The propane company come out about every 3 weeks to check and refill the propane tank if necessary. The first fill was $2.19/gal, $60 annual lease for the tank.
2) A Camco "Freeze Ban" heated water hose and heat tape on the metal pipe on the fresh water spigot. I power them off the power pedestal using a Thermocube outlet (turns on when it gets down to 35* and off when it gets up to 45*). I also put an orange Home Depot bucket over the spigot to keep the electrics dry and to hold in a little heat over the spigot. So far, this has worked to keep the water flowing even when it gets down into the teens. In single digits, I turn off the water as a precaution and use the water tank (always keep it full), but no problems yet.
3) We bought a dual analog control heated mattress pad at Penny's. Keeps things very comfortable at night.
4) We have a 1500 watt electric heater that we use to keep the coach warm during the day and at night. I keep the furnace at 60-65 during the day, but it very seldom runs, more for back up. The wiring in our coach does not get warm using the electric heat, but I do monitor it. Electricity is included in the site cost ($195/week including water, sewer, 50amp, cable tv), so I use it during waking hours.
5) For back-up, I keep another electric heater in the basement plugged into another Thermocube (I also keep a spare Thermocube, "just in case"). This heater has manual controls so it comes on when the electricity comes on. Electric controls have to be turned on manually every time. I set it to the low heat level and its thermostat set pretty low. If the basement gets too cold because of a problem with the furnace, this should keep things way above freezing. I also have a spare electric heater in case one or the other doesn't work.
6) I do keep the dump hose connected and dump when full, as normal. I do "walk the hose" to make sure all the water drains out. It hasn't had a problem. If it is buried in the snow, I dig it out so the sun will heat it up when it is not cloudy (we get a lot of winter sun here).
7) When we get snow, I go up on the fiberglass roof and sweep it off with a push broom. I do not want any ice to build up. I do not wax the roof before the winter so it is not very slippery. I have one of those folding ladders and use that to get up on the sides high enough to clean off the slide toppers.
8) We monitor the indoor, outdoor and basement temperature and humidity with two displays from Walmart and a couple remote temperature sensors. I pay a lot of attention to these to be aware of what is going on.
9) When cooking or taking a shower, I run one of the Fan-tastic roof fans or the microwave/convection vent to control the humidity if it gets too high. Most time the humidity stays in the low 30% range. I did use some Reflectix on the windshield but found that traps too much moisture and the insulation builds up ice on the inside of the glass. For the last several weeks, I just close the pleated front curtain. I close all the other day/night pleated shades at night. During the day, I open all the south facing shades to take advantage of solar warming. Oh, I also carefully selected the site at the KOA that gets the most sunshine, especially morning sun.
10) The best thing is to have a good attitude. DW grew up in Chicago and I grew up in Minnesota before moving to Colorado nearly 50 years ago. We both love winter. The dogs love it too.