Interesting idea. I generally add a switch to the ground wire for the rear lights for the track then pull the fuse for the front, I would assume you could just do the same with a switch for the front. Should be fairly simple, but where to mount that switch? I have a dpdt switch that I was going to try on the R7 for that instead of flipping a switch and pulling a fuse, just flip one switch that cuts the ground to both circuits.
I finally got to this today. Pulling the "SIGNAL" fuse shuts off all lights but the headlight (front sides, turns, tail, brake), "HEAD" turns off the headlight. If you just want the headlight off you could install a switch just for that circuit. Maybe a push button on one of the side covers connected to the headlight ground wire.