Met parabellum is sold with attachment parts for Go pro camera.I just tapped 4 mm treads GW:s baseplate and used longer 4 mm posidrive screw with inside go pro part.The one that goes to outside of helmet was not used.
I like to have light fixture as low as possible ,because of branches etc and it feels better balaced too.

 How does it attach to the helmet? Sticky pad or a strap through the vents?