We have a 4 season fifth wheel, rated for use to zero degrees. At least 50% of the heat from the furnace blows under the floor to keep things from freezing... only if the furnace is left on.
I run the RV antifreeze pink stuff once temps reach and stay at 32F. We use the camper every day in our driveway and sleep in it every night. Once propane usage (furnace) runs out one-thirty pound tank every other day, we navigate back into the house.
Our 5er is 40 feet long with 4 slides. If we run the electric fire place, the heat pump, and 2 electric ceramic heaters, the trailer still does not stay comfortabley warm enough to stay in once temps near 15-20 degrees. It's just too much space to heat. The furnace has to be running if we stay in the camper when temps are that cold.
Also, I found an exposed water line, no insulation, not in the underbelly, and in the clear open. It's under the slide and that line runs to the refrigerator ice maker. It would be the first thing to freeze up and possibly burst the line. So, winterizing the water lines, regardless of the claim to being a 4 season, zero degree usability camper is really not true.
I doubt very much electric heaters by themselves will add very little, except as stated above - an increase electric bill, and provide no protection against your water lines. Winterize the water system and if you need water in the camper, keep a milk gallon jug of water in it you can use, and do not dump anything down any drains or toilet. WE use a port-a-potty in the bathroom and dump it directly into our septic tank or directly into the toilet in the house every day, once the lines are winterized. This way we do not have to run in the house for potty in the middle of the night. (burr...)... Then we continue using the camper until propane gets too expensive.
Edit: Agree with the above posters about turning the wheels. Your plan is definately a waste of time. If you really want to exercise your tires, hitch up and go for a 30 minute drive a couple times over the freeze months. We normally travel to Florida and back again over the week of Christmas, and then to South Carolina in early March. This "exercises" our tires just fine. Never had a problem and never had flat spots.
Everything else you've done is good!
We don't have an on-board generator, I can't respond to that one. We do have a stand alone generator, and I fire it up once a month in the garage and let it run a while. Had it for over 15 years now, still working great. It was a free-bee we got with a new trailer purchase some time ago. The company was going out of business and giving them away to new RV sales and the next door RV dealership. We got one. It was a cheap-o-make and model, and had absolutely horrible bad reviews on the internet at that time. But, it's been running like a champ all this time and comes in really handy when we have power outages at the house. We never use it camping.
