I use the back up light wire to trigger a relay that engages the brake so the car can back up. It also has a trans brake switch that activates the brake, the feed for it is on a toggle switch. My brake will work in first or second and I didn't want to take a chance accidentally bumping the switch when driving it on the street. My two step engages anytime the brake is engaged but it's no problem.

You may have to run the feed wire for the delay box through a toggle switch to keep it from coming on while backing up.