Could the fork be drilled? If not, a replacement fork for when you want a brake? Pain in the arse to swap but that's what I have on my track bike for TTs etc
I've one of those that came with a similar fork. In the case of mine the black clamp had been forced to fit by being compressed, I assume with a vice of some kind. TBH whilst my fork is pretty slim your looks slimmer still. Something custom may be the better option.
Would like to find an alternative for this,
As the bridge / bracket is set too wide for the forks. Anyone got any suggestions?