[Christ]

I'd use pilot switches (the ones with safety covers on them) in the space under the radio, still mount a kill switch on the gear selector, but make it stealth, like it's supposed to be there. Perhaps on the front of the "knob"/"handle", just out of your middle finger's reach?

You could always foam-fill the areas that you want to get rid of on the bumper. That way, it's somewhat removable, and clean, since you'd be making a plug of foam, and sticking it back in the hole with foam mounting tape.

Other wise, thin polycarbonate and some very small L brackets, which would require at the very least, some small holes for retainer pins.