A simple table that folds up, will fit between the two beds. At night put it in place, then inflate a really nice queen air bed to fit over this platform. You have to crawl over the bed to go to the bathroom. In the morning, you can deflate the bed, simply fold once or twice and set on one of the beds. Put the little table on the other bed, and you have your hallway back. Ta-da! We do this with the dinette up front, but it's a real pain to tear down and set up each day. Yours will be so much easier.
Get the best air bed you can and get the 12 volt
version. That way you can inflate if your boondocking. You could also just tilt the mattress out of the way in the daytime, too, it's light enough.