You can make it child proof and original also (unless someone is REALLY snoopy) by using a Ford solenoid. Just mount the Ford solenoid in a discrete place with the cable from the battery on one side and a cable from the other side running on to the battery post on the starter switch. Now run a wire from the battery post side of the Ford type continuous duty solenoid up to your ignition switch "BAT" terminal and a second wire from the ignition switch "ACC" or "IGN" terminal back to the terminal on the Ford solenoid that activates it. When the ignition switch is off EVERYTHING is dead except the one wire up to the ignition switch. We do this to many cars/trucks for fire safety and to prevent battery run down when setting for long periods or if there is a drain in the system. Even though the solenoid looks just like a plain Ford solenoid be sure to ask for a continuous duty unit which runs around twenty bucks.

Evan