How to install internal overflow on established reef tank

[windcoast reefs]

Hey everyone

So im kinda sick of looking at my 2 corner drain pipes on the back wall of my established reef tank. Is there anyway to add small corner overflow boxes to the drain pipes without draining the tank completely?

Ive seen a few prefab acrylic overflow boxes in my LFS, so I was thinking of using those, just not sure how to secure them.

Any suggestions would be great!