I have not given up all my winter camping but in the past couple of years the weather has been insane and has put a crimp in my plans. -30 & -40 on the calm days and windy on the warm days that blows vehicles off the road. So I have changed my camping style.
Class C
Still have a class C that is well insulated and winter ready with 4 6V batteries for the house propane system, a emergency cat heater with 1lb propane bottles for when the temps cause issues with the house propane system and a third back-up 110v heater for when I have power. I stay VERY toasty.
Here is a link to my current class CClass B
What I have moved to using more than the C is a homemade class B. This has three batteries inside to keep them warm in cold (2 vehicle and one group 31 house battery), a gas Espar heater (no propane to freeze or fill), a porta potti (take inside any place and dump and no winterizing of a house water system) and easy to drive in the wind. I can easily spend a night in this in the freezing temps, it drives great in the wind (actually drives great in any weather). I also did not put in windows for a couple reasons; First is security - nobody knows what is inside, Second is no cold air leakage.
Read more on the van build here.Many of my winter trips are only a day or two, but if I am out for a long time and it is crazy cold I will stay at a hotel every couple of nights to use their heat & power and have a hot shower and I am all set.