Get two 1/4" male terminals, crimp them onto some 18 gauge extension wires. Now locate and take the reverse wire plug off of the column switch and plug in the extension wires into this connector end with the factory wires in it. Now route these two wires to your on/off switch and connect them onto the switch.
By doing so if you forget to turn off the new reverse light switch and then turn off the ignition switch, the reverse lights will go off and it's a clean way to do it to where if you ever do get the factory backdrive linkage you can put everything back the way it should be.
Jim