Ok, so once in a while I set my parking break (particularly when parking on a hill), and once in a while I forget to release the parking break before driving. After once or twice I think I'll remember to pay attention to that, but in case someone else drives it etc, I'm thinking it would make sense to disallow the vehicle to shift into gear while the parking brake is still on. That's the what and the why. As to the how: I'm thinking the simplest way to accomplish this is to use a simple relay circuit to essentially disable the regular break pedal sensor while the parking break is engaged (since the car has to see that the break pedal is depressed before it will allow shifting into gear). I haven't actually looked at the wires etc. yet to determine the viability of this idea, but if I decide it's the way to go, I'll post diagrams and instruction on how to go about it. Thoughts?
If you set the park brake properly, you shouldn't be able to move off with it still set. If you can, it is not set properly. Your idea does sound interesting, but I can't help you at all.
I've never seen a parking brake that would hold if you hit the gas hard. but it is super obvious something's wrong if you set the brake really hard, so at least you won't keep driving more than about 3 feet. you could wire a separate parking brake switch into the brake light circuit that cut the brake light signal. the car won't go into ready mode when you push the start button until you take the parking brake off.