First of all, thanks to everyone who has shared tips here. This is easily be single best winter RVing thread I've found, and I've been googling for a couple days.
Having said that, there is one thing I haven't been able to figure yet: almost all the winter RVing talk is focused on setting up long term in a park. I'm looking to stay mobile, not more than a few days at any given spot, and preferably not in a park. Is this all but impossible? Or doable so long as one stays out of -40 temps and doesn't expect a summer's day inside temp? (I am at 15C or less inside at home anyway, so I'm quite happy with cool interior temps) I'm guessing the biggest issues are going to be heating costs (even with a good insulated setup), and finding a place to get water and dump.
Of course, there is also the question of how well RVs do driving in snow. I'm open to the possibility of a more capable camper in 4x4 pickup setup (much better for heating of course) but have to admit the idea of something with space and amenities to hold off cabin fever for 3 or 4 months is tempting. Saw a killer price on a mid 90s luxury class A with a genset, usable shower and fridge, and even laundry that made for a VERY tempting proposition.