That looks pretty neat Musky, where'd you get that from...??
This thread is opportune, and reminding me of some discussion in a thread a while back, of which, due to my input Graybeards' words have haunted me- (if it's fitted it should work.....!),re;-
I have a conical front wheel with the matching switch block/brake lever, (well it's a Fonda wHour/magura lever, but don't tell anyone).
It has the integrated brake light switch which is connected, but it only works for a short time after I tend it- I suspect the plastic in the switch can't cope with the amperage (21W @ 6v=3.5A...?),- was thinking that relay idea that Graybeard put up may work, but a 6V relay is so far elusive- do they exist
Other option is just connect it to the cable switch same as what Bill had, but it just seems too after-thought-ish/tacked on, and cluttery
cheers