Chaos,
That couple of inches can make all the difference (no smutty remarks please!)
Riding in a straight line it would be just about okay, although I often squeeze my Pan mirrors through with no more than a couple of inches to spare, but trying to manouevre in town traffic would be almost impossible.
I remember a previous partner who insisted on getting the full Kawasaki-badged matching Givi luggage for her ZZR1200. One day while filtering through statioary rush-hour motorway traffic she suddenly ground to a halt. When she looked round she found her huge panniers wedged firmly between two cars!
BP