Re: Winter (below-freezing) use of Class B
When I was speccing my Sprinter out, there are some pretty cool Sportsmobile options:
1: The fresh water tank is completely inside the van, and you can drain the inlet that goes from the fuel fill to the tank (filling the tank by opening the rear doors.)
2: You can have a recirculation system specced out that takes some water from the water heater, sends it back via some plumbing to help keep warm drains and the grey/black tanks.
3: I was looking at a diesel hydronic furnace, when combined with a diesel generator (Powertech) and a controller from Magnum Electricity, it would keep the rig heated and above freezing. If the battery got low, the controller would fire up the generator for 3-4 hours. That way, if the "B" is topped off with diesel, it will keep itself above freezing.
4: Electric pads were attached to the grey/black water tanks. Those help, but seriously chew up battery life.
I like the fact that one could have a completely diesel Sprinter upfit, no propane whatsoever. The stove was a Webasto and exhausted to the outside, so the wet air from propane wasn't an issue.