The SoundCraft Ui design (actually SM Audio from Australia) is by far one of the very best mixers for schools and churches. Easy to understand and cost effective. However ….. it has a major design flaw. They should have made a model for installs with all the jaks on the back, but still have a pilot light and USB ports on the front. In lieu of that, I just make a mounting jig that spaces the faceplate back so standard XLR plugs can be used, and it is held in place good enough, and you can still use the USB holes, and headphone jak if needed. {the holes are already in the mounting ear, just drill through the rubber trim.} I use the white PVC trim board that is common at home improvement stores, and strips of 1/4”-1/2" plywood across the back. This works very well and holds it in place just fine. These mixers are infinitely better for schools than the horrible processor things I have seen lately, that cost thousands of dollars, and are impossible to figure out !
[I know I’m late to the party, so no comments about that. I just want to help anyone else with the same problem.]