The MCPCB is held in by pressure from the optic, but current FW3As have a set screw to prevent it from rotating while the bezel is screwed down. You would either have to drill out a small hole to accommodate it or remove the set screw itself, which I believe is threaded in from behind under the driver.
Hmmm… Nothing like a simple problem. Get a heck of a deal on a light I don’t particularly want, but maybe I should want, because if runs brighter and cooler…