I am considering hanging a screen from my vaulted ceiling, on the side with the lowest point and about two feet out from the wall. At that point, from floor to ceiling, it is about 8.5'. The screen weighs about 15 pounds and measures 67 inches in width. If I can't drill into studs, can I use the mounting hardware that expands on the other side of the drywall (I think these are called molleys)? I've used them quite a bit for mounting on a wall, but I am not sure if they are okay to use on a horizontal or angled surface like a ceiling.