On rally cars with lots of lights we used to put a AC clutch on the alternator, which was disengaged by a vacuum switch. This disconnected the load at high throttle openings to maximise car performance.
In the same vein we used to have a manual switch to disconnect the AC on a 1500cc Kijang in Indonesia. (Example below)
Mounted on the gear knob like an overdrive switch. Useful when passing logging trucks.