We are full-timing in the Salt Lake City area in our 2016 Grand Design Momentum 385TH. Been doing it for over a year now.
The unit has an insulated/heated underbelly. 12VDC tank heaters. Two 30lb propane tanks. No skirting. Temps where we have been ranged from as low as about -1F to as high as 107F.
We do not have a skirt. I want to add one, but money has been tight lately with medical bills from an unexpected c-section to pay off. I'm hoping we might be able to next year to see if we can cut a little of the winter heating expense.
First, get a Valterra Heated Water Hose. They work well, and are worth the money. It never froze on us. Cost just under $300 for a 50' hose.
Get a small section of heat tape and use that on the water spigot that you are connected to. Wrap that in pipe insulation. Total cost under $30.
For the sewer hoses, they froze up on us 2x. I have an outside faucet (inside a heated bay with the water connections) and hit them with hot water (externally) where the freezing was. About 60 seconds and they were flowing again.
I have 6 30lb propane tanks. I keep them filled, and on the coldest days (highs single digits to about 10F) we were using 1 tank a day. The furnace blows plenty of hot air into the underbelly, basement, and interior. We were able to maintain 72F inside, although it ran constantly on those coldest days. I supplemented the far side of the bedroom from the heat register with a small electric heater a few times as well.
With 6 tanks, I can usually go to the Pilot Flying J once a week to refill 2 to 4 of them and still have propane on standby at the trailer, plus the active tank. A few times I filled 4 on Saturday and then one more on Sunday to keep them all full. We could get a larger tank and have propane delivered, but this works for us. Propane costs for the 4 coldest months were about $250 a month. It ramps up in October, NOV-FEB are the most expensive, then it tapers off again to May. In the summer we go for 3 months with maybe refilling one tank (didn't last year, did this year) solely cooking. We use propane for cooking and heating.
We have a generator, but only had a couple of short-term outages and didn't resort to using it. The heat runs off of the 12VDC supply, and we have two deep-cycle batteries for that.
We have a small de-humidifier that we use in the bedroom and bedroom closet. We have a washer and dryer, and would not be without them. It's sufficient to keep things from getting condensation.
Use Reflectix over the windows on the inside. It makes a real difference.
I hope that info is helpful.
