If you can find/afford a coach with diesel heat you will also be much happier with your winter camping. Aqua Hot/Webasto and similar setups us the coaches diesel fuel supply so running out is never an issue. It also does a much better job of maintaining a steady temp vs. the hot and then cold and then hot with the propane furnace.
One issue you will have to deal with is keeping the unit winterized (or not) when you are not using the coach between trips. If you choose not to winterize you have to keep it warms so the water lines don't freeze. If you do winterize you have to choose whether to de-winterize for the trip or not use all the facilities you wanted to use when you bought the coach. We used to go to 7 Springs in our entry level diesel pusher but it used propane heat. It was wonderful and we stayed on-site without issue. Our new coach has diesel heat and I simply would never go back. It really proved itself when we spent much of last Winter in Detroit!