From what ive seen out camping in the dirt as the kids reach that age they prefer to do their own thing. Bring out tents or sleep in the truck. Only using their parents rig for the restroom and shower. Might be a little different because of all the open space dirt camping. My advice would be to focus on what works better for the parents, because the likelihood of the kids staying with you in their mid 20s becomes less and less. If they do decide to stay with you sleeping arrangements are not all that important. Air mattress on the floor works just fine for the few nights a year they might come out camping.
