I think that Willrick should have a Sanity Bonus, since in this game, flowers increase sanity, and in real life, Plague Doctors put flowers in the beak of their masks to hide the smell of dead Plague victims. I guess then in the DST version ghosts should not decrease sanity, at least not as much. Specifically, the flower they put in the beaks was lavender, which actually increases sanity in real life.

Often, their remedies only worked due to the Placebo Effect, so he should have some sort of item that changes effectiveness based on sanity. Or, maybe, if his Sanity is low, things like Monster Meat GIVE him health instead of taking it.