For winter camping you need plenty of BTUs and plenty of fuel to convert to BTUs. Any coach that has a AquaHot will do well in the winter as it meets the above requirements. That said, there are still areas that require special attention... the ice make water line and the bay area where your dump valves and water lines are located will need some extra insulation or supplemental heat. Keeping some of the slides in will help too as most are not as well insulated as the rest of the MH.
Nailed it. The one 'extra' I do is put 100 watt light bulbs in some of the bays. Amazing how much heat they toss out ... but your electric bill will be ... don't ask.