I just remembered that René Herse did make twin-plate fork crowns on special request, even on bikes with brazed-on brake pivots. The fact that these were available for 30+ years indicate that they must have been problem-free.
The plates are quite beefy compared to those of a typical racing
bike, see
http://www.mindspring.com/
And I hope that is the last I'll say about this! One minor comment,
and it almost spiralled out of control, because like most things,
it's more complex than one thinks at first.
--
Jan Heine, Seattle
Editor/Publisher
Vintage Bicycle Quarterly
c/o Il Vecchio Bicycles
140 Lakeside Ave, Ste. C
Seattle WA 98122
http://www.mindspring.com/