Thanks, Garth and Steve. I've considered that before, principally to avoid the causes of shudder, but the biplane crown is not drilled, and I expect (have not peered under the hood) that the requested-beefy under-crown threaded fender boss will interfere with any bolt run through any hole I drill there, just as it did on other bikes with front caliper brakes. And the Paul's are precisely constructed enough to fix the shudder that the earlier Tektros caused without (almost) 45* toe-in. What I'd really wish is that Minimotos could fit over 42s and 50 or 55 mm fenders to work with my DA 7410 brake levers, but alas ...
Right now, for record, I have a -- Shimano? Forget, but I think it's Shimano -- sturdy steel headset-mount hanger that is plenty stiff but that has only about a cm of drop. The RH will double that for a less cramped housing run from the inner end of the bar tape.