I believe that is about it. There are a few other 'oddball' options though involving your overlay and plastic or some other material.
- Recess a space into your plexi overlay so the bolt is in that and not 'sticking up' on the CP. Still visible, but you won't touch it.
- As above, but put your CP graphic ON the plexi/hardboard/whatever overlay material you use first. If you want plexi on this, it might get a bit thick.
- Construction glue or weld support structures (wood or metal, respectively) to the bottom of the CP. Use these to hold everything in place.
I'm not totally familiar with it, but I think 3 might be the best option if you can 'bottom mount' the controls and JB Weld would be strong enough for this. You could do a very high surface area mount that covered nearly the length of the CP, then drill through that along with the top CP.