Lyric Kinard has several tutorials on mounting and framing art quilts.
http://www.lyrickinard.com/tutorials.html
Her work is much smaller than yours, but there's no reason the same process wouldn't work for you. I've used several of them and they look great.
Whether to skip the show or replace the back would depend on the show rules, but the piece would certainly be worth mounting for your own enjoyment. Sounds like the front came out beautifully. Welcome from an ex-Michigander. ;)