We have made a number of quilts with old jeans for charity quilts to go overseas. We use a light weight backing, a thin batting (just thick enough to pad the seams) and tied them with crochet cotton. From my experience sewing denim, you are in for a lot of broken needles if you try machine quilting over those thick seams.

try fleece as backing--soft and warm and no need for batting stich in the ditch press seams open this has worked for me your quilt it great !