Maybe the way around the problem might be to rent a Class C from Canadream or one of the other rental outfits for a week. That way she can see the error of her thoughts. Won't be cheap to rent, but if it saves you from buying a MoHo and then going back to a truck and camper then it may be well worth the cost.
My DW was having mobility issues a couple of years ago and we looked at some nice Class A and Class C rigs. After that she decided that the TC was the best way to travel, and now she is even considering selling the TT and keeping the TC and only having one camping unit.
Good Luck
Brian
