ben2go,
The way the DF is designed and shown in the electrical diagram there is a switch called the illuminating switch that would do what you said. You could turn on the position (parking) light on or off with the ignition switch off so you are not completely blond.

But since the US requires that the headlight on motorcycles be lite when the engine is running the DF wiring has been modified to meet that the requirement. I'm trying to figure out how to reverse this change hoping that it will fix the headlight dimming that some are experiencing. Also I would like to be able to turn the headlight off if need be because a failure of a electrical componet.