Hancock Fabrics has some vinyl coated fabric for raincoats in colorful prints. I think it's 60" wide. That would work for the back of the quilt and it's obviously meant to be sewn. I have used a WalMart soft vinyl shower curtain to line make up bags I make. It is harder to sew with. I found that it helped to use a foot made for vinyl or leather and a stretch needle and stretch stitch selection on the machine. Good luck! If you do make one with a vinyl back, please show it to us when completed.