Due to a house move, we spent about 6 months in our 35QB4 last summer (erm, spring, summer, and fall actually). I agree, the jackknife sofa does poke out a bit into the pathway to the bathroom, but it never felt in the way. Never gave it much thought actually. Not the best design, but better than one bathroom.
No, the baggage doors don't lock open. I have a tie-down strap on each side to tie them off to the front landing gear if I need to keep them open for a while.
2014 Silverback 35QB4
2012 Ram 3500 6.7/slushbox