In the real world changing the reticle(what we call the gunsight in AH) was performed on the ground after the optical device called the gunsight, was pulled out and dismanteled by your ground crewman. Then your fighter had to be hard standed at the gunnery range while he re-harmonized the gunsight\reticle back to your guns.
At best, wishing for Hitech to make the alpha slider a dimmable button toggle, which represents the rheostat for the internal lamp, an active cockpit component is realistic. Or simply an on\off toggle.
Switching between too many gunsights too frequently may not help your Hit%. Though, for my AAF rides I have them setup with the AAF reticle related to the primary job I fly them for. The Axis seem to not have used the concept of a fighter bomber specific reticle like the AAF and RAF. And to begin with the first bomb aid for AAF\RAF fighters was a tilting sight head. Germany had a tilt able base mount for the Revi16. Only the AAF by 1944 added a rocket\bomb aid structure to the N9 101Mil reticle and K14A fixed reticle.