Have done that before and it will work fine. A couple of things, one place a piece of masonite on each side of the slot glued to the foam scenery. This will give a firmness to the slot and will keep the divider from wobbling. Second, don't worry about making the divider too high. If you are taking it to schools remember that the kids aren't as tall as we are. A lower layout hieght, possibly about 30-36 inches and a divider of 24 would make total hieght about 54-60 inches plenty high to block line of sight for elementary students.
my two cents
Randy
Am working on a portable 4x6 to take to local school, maybe other functions. Plan to have a scenic divider to make the layout look bigger. Have a 2x4 sheet of masonite that I will use (may not use the full 2' height), but am thinking of having it removeable. Has anyone tried having a deep slot in foam insulation board mountains to hold the divider in place? How'd it work? Other suggestions on height of divider, ways to hold it, I'm open to suggestions of all kinds?
Thank you,