We winter camp a lot in the U.P. of Michigan or in Ontario, Canada and have for over 40 years now in far below zero F temps and are always warm. We'll have it NO other way!
If you can run a 110V AC extension cord of only 10 amps or more, put either an electric blanket on the mattress or a heated mattress pad and cover it with a good blanket. Turn it on about half way or like 5 on a 1 to 10 dial or readout. It will take the cold out right of the mattress in only a few hours. If you can get 15 amps to the TC or any RV, also turn an electric heater on the low setting and it should only take 7 to 10 amps and will be more than enough to heat any decent RV to about 55-60F or warmer and will take the chill out of the wood and the rest of the RV's interior and make it so much quicker to heat up when you want to be inside after your traveling. It also dissapates a lot of the moisture in the inside air as warm air lowers the ambient humidity levels. You'll surely add gobs of humidity with your breath when inside when it very cold outside.
If you don't have 110V AC available, no problem! Use a 350-400 watt or more inverter to power the electric blanket or pad. One group 27 battery will run a blanket or pad at this setting for 24 hours if the outside temp is 20 F or higher. The battery recharges while you drive and is still powering the electric blanket or mattress pad and the be pre-warmed bed is ready when you get there. Having 2 or more batteries will even work better. To heat the inside of the TC before you get to your destination or beginning the night before you leave, turn on your RV furnace and set the thermostat to 55 or 60 F and we leave ours still on the low heat setting when we travel if the outside temp is below 45-50F. Been doing it for approx 50 years now and have never have any problems and our batteries are always fully charged when we stop for the night. It take a surprisingly little amount of propane to do this.
Yes, you can use a 12V DC blanket or pad and get the same results but having an appropriate sized inverter lets you use other 110 appliances, chargers, items etc and they are nearly silent when running unlike our 110V AC generators.
Winter RVing and camping is outstanding an we love it. Also, there are a lot of CG's here in Michigan that are open all year and several have heated showers and bathouses but the dump stations are usually closed as the water would freeze. Simple to get around this little bump! Use a porta potti and put the windshield washer fluid with anti-freeze in it in the top rinse tank and it keeps the bottom contents from freezing even in below zero F temps. Dump the bottom contents in any toilet anywhere and use 1 or 2 etc gallon jugs of water for sponge baths in between showers. There will be no water in your lines to freeze or water in your fresh or holding tanks. Works great always and has for for 50 years so far!
