I don't think yellowing will be a problem for a Stewart. If you note that the unit is going in front of a window, Stewart will manufacture the screen from three layers of material, the middle layer being black. I understand that they do this to increase the opacity, but it should minimize the discoloration of the viewing surface. There are other potential problems. Most of these projection screens change in size quite a bit with temperature extremes. Further, I have seen screens that became tacky to the touch (and picked up quite a bit of dirt)from off gassing of the vinyl material (not a Stewart BTW). You best bet is to contact the various manufacturers directly, describe the setup, and get their input.