It really seems like locking the front panel and the control panel together is the way to go because it is simple, works very well, is easily accessible from the front, and accomplishes locking both the front panel and the control panel at the same time.
Along this line of thinking, I had another idea for a locking mechanism: bolting them together. If you could turn a bolt that was threaded into the front with the head above the control panel, you could pull the front and control panel together (see diagram below).
I've been toying with automating this project so I purchased
this DC motor with a gear train and threaded rod attached. I didn't realize how comically small it was which is dumb considering they include a picture of it next to a coin. But, I tried it out anyway.
I made this little test setup:
I routed a channel for the motor to sit in and prevent it from spinning then I cut the slit for the washers and stationary nut to go in. Doubling up the nuts at the end lock them to the bolt and prevent them from spinning freely. This results in the motor, rod, and end washer moving away from the base when turning clockwise and towards the base when turning counter-clockwise.
It seems to work pretty well especially for how tiny that motor is. It creates a nice tight fit and the force on the joint goes from the wood to the washes to the nut to the threads and not on the motor. Next step is to mount it to my test rotating control panel setup.
Here it is in action: