Welcome to EM
How about partailly electric P/S? The pump is electric, not belt driven, and you can have it turn off above a certain speed. Or just disconnect the pump and drain the fluid, that's what a few members have done.
As for switches: Maybe an alternator kill switch? Turn the field wire on when accelerating and engine braking, off when coasting.
Also, a switch for a manually operable grill block.
Mine is opened/closed with a power lock motor.
Hmmm, what else? If you have A/C, you may want to manually control it. That is, if it turns on automatically, as mine does, damned engineers
