I agree with brholt’s comments. If you want to do any serious boondocking you need to think small, high clearance, and 4wd. Small might conflict with your “showers in the winter” idea since small units have limited capacities for water, propane and battery power and boondocking is generally an exercise in conserving resources. I don’t know if there’s a “type” of RV most suitable for 4 seasons, I think it’s primarily whether the type of unit is built for severe weather.
I’ve driven a lot in severe weather conditions in the mountains on hunting trips with a 4wd TV and a PU and small TT. While I wouldn’t call it white knuckle, neither was it “easy”. There’s always a degree of tension about hitting a patch of ice, navigating narrow, rough roads, especially if they’re snow covered and you can’t see the ditches, and getting stuck in the mud. I’ve stuck my 4wd a number of times. Sometimes I could get it out, others I just hunkered down and waited until the middle of the night for the ground to freeze and then drove out. I rarely used the TT, even my 16’ 3000# TT was a handful in those conditions. The PU worked OK, but it wasn’t ideal for severe weather. Again the issue of capacities and keeping it heated.
I wouldn’t consider driving a Class C in those conditions. Maybe a TC or 4wd B. Even my small TT was OK if I didn’t try to get much off the pavement. Of course in good weather conditions just about anything would work for you. But for boondocking I go back to my small, high 4wd comment. Good luck.