A couple of thoughts: many RVs call themselves "cold weather units" because they've kept the tanks in heated spaces - but the low point drains and the sewage valve are still hanging outside the box in the cold - duh! That being said - we as Michiganders, have always camped in sub-freezing temps by flushing the toilet with antifreeze and using a jug of water for teeth-brushing, coffee, etc until we got into areas where the temps stayed above freezing.
And personally, I prefer a Class C: you get all the vehicle safety features provided by the factory for the chassis; the driver and passenger each have a door; plus there's all sorts of storage overhead. It's fairly easy to find accessories (like moose bars) for a van; and windshield replacements would be cheaper....LOL!