I had a similar situation. My table was a solid core door, too wide for most clamps. I purchased a 4x8' piece of high-density fiberboard and had it cut into four 4x2' sections. When I needed to sandwich a quilt, a laid out the pieces of fiberboard on my table, clamped them together with office clips, and used the office clips to hold the quilt back on the board. This had the added advantage of giving me a much larger work surface, and the office clips are inexpensive and easy to use. When I wasn't using the fiberboard it was easy to move it to the side and and it didn't take up much space stacked up against the wall.