OP, not sure if your going to be in it during the winter, but building a cover to cover the WHOLE coach w/ slides out to keep snow off is 1st. Plan on using a LOT of propane to keep heated. Really no way to keep water/sewer lines from freezing (assuming you have a sewer hook up). With a 5tyh wheel, you have the underside of the hitch area open and hard to keep warm unless you make some kind of insulated enclosure. Like what others have said, I would highly consider a cabin instead or a cottage RV.
On the Montana front, yes you see a whole lotta them on the road pretty much cuz they are probly they have the largest dealer network (ie: Camping World). I do tip my hat off to them for a lot of different ideas, floorplans and all. Likewise, I agree w/ Cummins that Montana as of most recent, their quality has improved.