https://www.trailmanorowners.com/for...ad.php?t=12848
Look at that thread. The bunk bed(s) span the width of the space. The fold-out bed also has removable arms to make more space -- I didn't realize that until I started the project. I'm not sure how much more length the QB will have -- I don't have that model so I simply don't have that answer, but I'm sure someone else will chime in. A particularly tall person may have an issue on a QB, in which case the best bet is a mattress or cot lengthwise in the "hall"...in which case the added hall/space of the SL would be beneficial.
My family isn't particularly "tall" so it's not been an issue for us, yet.