I will have a clearance issue with the Low and High knobs...thanks for pointing that out. There is a solution: there is about 25mm of unused PCB on the front of the Ch.1 and Ch.4 vertical boards. This area was originally mechanical support for the channel faders. I can make a straight cut with a hacksaw on each of these boards to make room for those two Isolator knobs.
On the Isolator version (I'm using this faceplate as a testbed to make some tiny refinements, it will never be gigged) I'm going to move the Channel knobs down maybe an inch, which is the amount of spare space I have before hitting the bottom board.
To clarify, the Isolator circuitry will be in a chassis above the MP24. The knobs will be tethered to that Isolator circuitry. That fits my specific needs in this case but might not fit the needs of others.