I too float my quilt when quilting. I baste along the top, then before basting the sides I smooth the quilt down to the bottom (out of quilting range) and pin. I place several pins across the bottom to hold the quilt in place. Then I baste the sides, add side tension, and quilt a row. When I move it up for the next row, I pin the bottom of the quilt again, out of range of the quilting, baste the sides, remove the old pins, add tension, and quilt away. They usually come out pretty square! Ann