size does matter
When we built our house, I wanted a "larger than normal" garage. I'd been in the typical 20x20 garages and they seemed too small for a truck. Ours is 24x24 and it would be almost too small for a QC-long box. My QC-short box has about 3-4 feet in front when I leave 6 inches at the rear. It is wide enough I think, but if you had a long box, you might want a few more feet in length.
I put 8x9 doors in and wish I put 8x10's so I would not have to fold the mirror in to pull in. I don't HAVE to fold the mirror, but if I'm not REAL careful, battle damage will occur!!
Just my opinion and that don't count for much.
Chris