Okay, long time no see, but update: got in touch with Hodgdon after Winchester and Hornady were both less than helpful, and I now have load data they gave me based on "bullets of similar construction". All is good there. I intend to load five at minimum then five each 0.2 and 0.4gn above that, so long as I am still 0.2gn below maximum. That should keep me safe-ish, but any hints on pressure signs in the 9mm would be helpful. Needless to say, I will be firing for function at first, so close I can't miss, to ensure that the bullets have left the barrel. Once that is established, I can start accuracy testing.
The Hornady bullets have a published oAL but the Winchesters don't, so I'll be trying max listed OAL first unless that seats the bullet out too far to hold in the case well or causes feed issues, then I'll seat halfway to putting the parallel part of the projectile all in and adjust from there.