Mine is different.
Rimmed 120 tank.
I siliconed T slot 15 series to the top rim.
Added door sliders to top so ati unit can slide out of the way.
Slider on bottom is siliconed on for more surface area to rim.
Ati unit sits 4" off the water and all light goes into the tank.
With 3D printers getting into the mainstream, I hope someone starts manufacturing some sort of holders that would snap on the tank wall (sides or the back) while holding on to the ATI fixtures.
ATI promised a new light stand a few years ago.
I think I remember a picture. Maybe a prototype?
I looked all over at as many diy solutions as I could find and nothing really worked for me.
I always said going with the ceiling mount was not going to happen. I just thought it was ugly.
But then I gave it a try and was mildly surprised. It was ok.
After 2 years, I'm glad I did it.