I did look up the dimensions on that last night as well and saw the 110mm (4.34") width would be a perfect fit for the bracket inside. By acrylic extensions I'm assuming you mean you're increasing the length of it from the 250mm. I modeled the sump in CAD a few weeks ago and believe that area is 345mm (13.6") long.
Your control board idea is nice as well. I ended up screwing a piece of black plywood to the back supports cut to shape to hang my power bars, UV light, ATO pump and a few other small things, and all the controllers are double sided taped to the inside of 3 doors.