when you cut the slot for your sewing machine to slide into the foam (use the free arm to measure the cut) i taped the vinyl table cloth on the sides of that slot.
i placed the table cloth over the foam, slit it down the middle of that slot and then taped it down with duct tape all along the inside sides of that slot.
this way the machine can slide into the foam without disrupting the vinyl table cloth.
then i have a supreme slider which i place over the free arm of my sewing machine. the supreme slider is a teflon 8.5 by 11 sheet that makes the transition from foam to free arm seamless.
it doesn't look very pretty but it works beautiful. i'm quilting a king size quilt on it and it moves with total ease. i never would have been able to do that before. i'm more concerned with things working well then how they look.