One fault with the "secret switch" idea, is that you can simply pull the kill wire from the mag and ride away.
I use a humungous lock and chain, and have a ground anchor in the garage, car parked in front of the doors. If that fails, there's always the 12 Gauge.
Seriously though, you might not be able to stop a thieving b;stard taking it away, but you can make life difficult, the longer it takes to get through your chains etc, the more likely they wont bother.
In fact, based on the theory that I have to open the garage doors to get the bikes out, therefore giving sight of the bikes, I always make a big show of fitting chains locks etc with the doors open so if anyone is watching they know that they would have several serious chains to cut through and that would take some time. F'kum