I float my tops as well but I do attach to the top of the backing and batting at the beginning with a row of horizontal stitching. As I roll the layers, I baste down both sides being careful to keep the top square. I only side clamp the backing fabric and I don't overtighten the layers. If my finger can push up from the back to the front and I can grab up to the first knuckle, then that is good. I like to quilt as much as I can as I go down. If there is a lot of SID, I will do that first and then go back to the start for the other design work. Rolling back & forth does seem to cause puckers in some areas of the quilt, but usually as you get to them, they will smoooth out. Try using small water bottles on either side of your needle when you get to a puckered area. This should smooth it out and the puckers will be eased in. Good luck.