Occasional Winter Camping??

I spent a couple months on the road camping in winter before. My best improvement was putting a couple sheets of lattice fencing in the cab over for breathability with 1" RMAX foamboard on top under the mattress. That greatly helped keep the bed warmer. The other thing was to get a set of heavy flannel sheets. That was one of the biggest helps. Another trick I used was to sleep with my head at the foot of the bed, so it was more in the center of the camper and my feet out front of the cabover. That kept my head and body closer to the warm area of the camper and my feet in the colder area. I like having my feet cooler. I like my comfort, so My furnace is set to not less than 62 degrees at night and 65 or 70 in the day, whatever it takes to be comfortable. I have 400 AH of lithium and 675 watts solar on the roof, so power is of no concern excepting for clouds and shade. Charging gets better the farther south you go in winter. If I fall short of charging after a couple days, no matter because I'll probably be relocating to the next location and the 30-amp dc to dc charger will recharge the battery system back to full in the time it takes me to drive to the next location. If I stay at a site with electricity, I have a 1000-watt 3' wide baseboard heater that works well down to about 25 degrees, then I need to supplement heating using the furnace. I think 5 degrees F is the coldest I've camped. Keep in mind I have measured a 30-degree difference between the floor and the countertop in the TC. In the real cold conditions, I have a small fan that blows cabin air down into the basement for the holding tanks. The tanks do sit on top of 1/2" Styrofoam, so they have a little thermal protection. Get some really thick slippers and socks for hanging in the TC because your feet will get cold in those conditions. OK, those are my tricks. That's how I stay warm in the winter.