I've been thinking about this too. Since I like to take my duvet cover off and wash it more frequently than the down comforter I like the idea of a removable cover. So... I thought about putting a fusible interface on the back of the quilt top to anchor the seams and then attach a backing like a giant pillowcase. Not too sure about your quilt top design, but you could 'quilt' some of the top to the interfacing. Do you think this might work?