Don't know what make/model fiver you have, but here is what I do until we head out in December.
Ceramic heater in basement, which not only helps keep my convenience center warm but keeps our bathroom floor and most of our bedroom floor warm.
Plug-in heated water hose. 3" PVC pipe for my sewer drain instead of stinky-slinky. I use 3" rubber connections/elbows to make the exact run. You can even wrap it with some insulation and duct tape if you want.
After every black tank dump I start by adding a gallon of RV antifreeze to my black holding tank. When I dump my black tank the only way I rinse it is by dumping buckets of hot water down the toilet, then opening the gate valve again, before closing it and adding the RV AF.
We run two other ceramic heaters inside, both tower types, plus the electric fireplace. During the day we don't run the furnace much, but at night ceramics get turned down and we keep furnace on about 60. Our unit has a duct drop into the underbelly so by running the furnace it helps keep the area around our plumbing and tanks warm.
Anyhow, welcome to Illinois winter camping. This is how we get by without skirting. It was -2 windshield this morning when I got up and so far so good. We are going through about 30 pounds of propane every week right now.
2014 Montana 3725RL (Goodyear G614 Tires, Flow Thru TPMS)
SPENDING THE WINTERS AT OUR HOME IN SW FLORIDA. THE REST OF THE YEAR SEEING THE U.S. FROM OUR LIVING ROOM WINDOW!