I will see when the light and the mount get here, but I think it will interfere with the glass top. It's hard to keep the glass clean, and It seems like every nicely lit reef tank I've seen, has no top. Maybe I was wrong about that. I'm buying the mount from Reef Radiance too, because I can't hang it from the ceiling.
I don't want to block or filter the light from getting to the water. Was thinking about black egg crate but I think that will block the light from the 90 degree LEDs that are supposed to help cover a larger tank area.