[Christ]

The last time I did something like this, it was a hand controlled throttle built from a bike's brake handle. (I drive with one hand on the shifter most times, except if I'm racing.)

Obviously, it required a slightly heavier spring on the throttle, but I set it up with a cable clamp that just made it pull on the accelerator pedal's cable, instead of changing the throttle cam on the throttle body.

I got so good at driving with it, I could drive with no feet after starting from a stop, by using the hand throttle and speed matching my upshifts and downshifts.