I don't think you mean actual 22.5's like the tractor trailers run, do you? Or just a fat (wide) tire for the rear for looks? When you guys say Super Single, I think of big rig tires. My friend had a ford dually with fat tires, I thought it looked good. As for getting a flat, if you go with a fat tire, who says you can't use a regular wheel as a spare? Duh! It would store in the regular spot and be good enough to get you home.
Let me know when you need more good ol' fashioned common sense.