I roll mine up. The side that goes into the harp of the machine is rolled. I tried using bicycle clips to keep it rolled - some roll both sides and keep a flat center area of about 9 - 12 inches - but the clips didn't work for me. So I just roll the one side. I have only made one very large quilt and I hand quilted it. I have used a lowered ironing board to catch the quilt on the other side of the sewing machine but it was more problem for me than help. My sewing machines that I use to quilt both have sewing tables so there is enough shelf behind the machine it seems enough to hold the quilt.
What is your sewing machine sitting on?