Chris, I have not looked, and it is probably more primitive than what you had in mind, but could you remove a fuse for the time being. Maybe even disconnect the sensors at the front of the car. Im not sure where they are on the new edge Mustangs. On the fox bodies they were in the space between the radiator and the bumper cover, near the top.
As crazy as it sounds, if you disconect the sensor on the front bumper of the 2000 R, it becomes extremely difficult to get the car into reverse. The rest of the gears work fine but it takes two hands to force the transmission into reverse. :shrug: