This is a great project and one that I have thought I would like to do in the future although I hadn't thought about the Sky Deck but it makes sense, on many boats I have been on the fly bridge is always the main hangout.
I agree that an entire room dedicated to a bed seems like a waste on a camper and I also use my little toy hauler as an office and classroom so I was thinking about putting a futon up there, we have a very comfortable one for sitting or sleeping, and a desk to use as an office.
BTW I don't have a fiver yet, mine is a little TT toy hauler so these projects will have to wait until I upgrade.
I look forward to seeing more pics. Good luck!