I have started a new layout and made my tabletop from plywood. I have "switched gears" in that I would like to use foam now. I have noticed that alot of people eliminate the plywood when using the foam. Is it still possible for me to continue by laying sheets of foam on top of the plywood and go from there? I plan to use cork roadbed so then my next question is how do you secure roadbed/track/scenery to the foam?