I don't really know who things worked with getting the Vampire Hunter into the builder, but is it possible the Omdure might get in? It is from Paizo, but in the similar vein of the Vampire Hunter D stuff was released through the IP owners. They seem like they would be in favor of getting it into the system.
For reference, the class:
https://www.d20pfsrd.com/classes/base-classes/omdura/
There are also some new feats, races, and archtypes in the same Niobe book.