How come you router guys don’t do this the way the aerospace folks vacuum down a wing section? Just lay down some particle board on your bases (the same size as your base), then deck the surface so it’s nice and flat. Make sure your vacuums on though. Then just place your work piece on the top of the particle board but place thin sheets of sheet metal of some type on the un-used areas of the new table surface to maintain a decent vacuum? And if you still have small voids here and there, lay down some masking tape in the exposed areas. It works pretty darn good holding down metal & aluminum, I don’t see any reason why it wouldn’t hold down a block or piece of wood!