Used them a lot in a cabin that only got used on weekends for snowmachining. We actually used a heated mattress pad and not a heated blanket. When we'd get there Friday night, we'd turn on the pad, start the wood fire, take care of a few things and go to bed. By then, the heated pad would have the bed nice and warm. Don't know why it would be any different in a camper.
We used the mattress pad instead of a blanket because it seemed to work better with the heat rising from the pad instead of trying to get it to go down from a blanket.
Bill