Control automotive AC switch via TPS voltage
on some cars (scion tC) it's simple to remove the climate control unit from the dash. Behind it is a cable with 30 odd wires coming out of it, and a wiring diagram tells us which wire feeds (somewhere else) to (something else, presumably ECU) that handles actual compressor control. Installing a Reed relay in series with the correct wire, and wired "always on unless small comparator circuit triggers" could work. If you need a schematic I could edit one in.

the scion tC ECU is supposed to sense and disengage the AC clutch during heavy acceleration, but that doesn't happen.

Your question has inspired me to do this for myself. It might be good to implement a delay circuit so that the relay doesn't cycle with every shift (if yours is MT like mine). My original thought was to manage cruise control and AC state based on OBD2 data to keep AFR at the engine's preferred 'stoichiometric' 14.7:1, e.g. slower uphill and maybe AC off, faster downhill. At that point, it's not too much extra to add a laser distance detector to sense distance to the car ahead of you to automate cruise, which is what really would be nice.