I have no first hand knowledge of your rig so this just my thoughts on the subject.
I would say you would not have to have all the slides out. It just does not make any sense to have to put all out. Looking at your floor plan I would guess you are thinking about the bedroom slide more than the other two. With that said the living room slides might be a different thing. As for balance I could see what past owner was talking about, it would make sense to put both out. However for an overnight I would put out what is needed for the night.
Good luck
