The main reason for it to "float" is to allow for expansion and contraction with changes in temperature and humidity. Over a large span, if you nailed down the edges, and each piece expands just a smidgen, all those smidgens add up, and the floor buckles. As small of an area as the camper floor is, I imagine just the slop inherent to the joints would absorb the expansion... Also, if you nail down the sofa, the other end is still free to move with expansion. I just today nailed down quarter round as trim all the way around the front of my floating floor. If it buckles, you'll know about it from the whining and crying in my rebuild thread....
Somebody ought to clean these windows. There is a tremendous buildup of gook all over them...