That's a beautiful quilt. I would attach it; it may look a little different on the back but would it be a place where you could put your label? Appliqueing the label in that area may cover the difference altho I don't think a slight change in the quilting would be that much of a judging factor. Good luck, let us know what you decide and how you do at the fair. Looks like a winner to me.
(This is a suggestion from a very anal person so I know why you're concerned LOL)