I have a '74 Argosy with twins. In looking at it, unless you can make something that folds up to give you access to the bath when not in use, it's not very handy. Even at that when the bed is out you have to crawl off of the end of the bed to use the bath. Here is my plan. The bed is 76" long, so I'm going to cut 2 pieces of plywood 38" long by 28" wide ( the isle way is 26" wide. These boards will be stored under the mattress on one of the beds when not in use. When I want to make up the double bed, I simply slide the boards out and across the isle and cover the walkway. The only reason they are 38" (1/2of 76") is to make them easier to handle. Once the boards are in place I'll simply slide one mattress next to the other, blow up the air mattress (double bed size) lay it on top of the twin mattresses and WAHLAH! A double bed. Still have to climb off of the end to get to the bath. But, I can live with that. AT least until I can come up with something better. With this setup, you have the choice of which side of the trailer you want to sleep on, depending on which twin mattress you move. That may be a plus in some camp ground with a street light that shines in one of the windows.