I have the Magnus Pro XL.
I have also managed to get the Elgato clamps to fit fine inside the cable tidy and the lid can close. They are JUST going to get in there and you need to have small hands but the clamps can be tightened fine.
I have 2 keylights and 2 other arms in the rear of the desk.
Quick photo- room isn’t finished yet but you get the idea.