I also think it will be hard to do a dense decorative stitch on the binding. How about doing your decorative flower row on the quilt top where you want it but about 1/2 inch in from the edge, and then do a facing binding. A facing binding is sewn with however wide strips you want on the edge at the 1/4 inch seam allowance and then the whole facing is turned to the back and hand sewn to the backing fabric. You could make the facing as wide as you needed to cover the backing shortage.