Sandwiching a quilt is really no fun but must be done! I have 4 x 6 piece of plywood over a table. I also use 505 spray basting which makes the process easier and keeps layers from moving! Another trick that I do is to start laying out the quilt at one edge rather then from the center. This means that you only have to move quilt 1 time. Just make sure you position the layers so there is enough backing/batting/top to cover all the layers.
****This method works good when the backing is just one fabric.