Winegard does not want to sell something specifically listed as not to be used by RVers. If you look at a Hopper as it comes out of the box it says "Do not move while plugged in". They are talking about not moving the box in your house, much less driving down the road and beating the bejesus out of the box. Dish does not want the hard drive to break. If you don't believe me, call Dish and tell them you want to have a Hopper installed in your RV. Let me know how that goes.
The only thing needed to make a Hopper work in an RV is a Trav'ler (or home DPP LNB antenna) and a Solo Node. The Solo Node is the thing that Winegard does not sell but it's readily available most anywhere.