The "Wild Hunt" thing could possibly work in two variations: one for the Norse religion, and one for cultures in the West. Something about the description of "a group of spectral huntsmen in a wild pursuit of something across the sky, land, or just above it" just sounds like something I could imagine being dreamed up by ranchers and cowboys too, although they'd probably use simpler terms, something about "ghost riders" trying to catch "the Devil's herd" in the sky. Something like that, I dunno, it probably sounds really silly and I doubt any Westerner would actually sing songs about Riders in the Sky.
As for the Folkish stuff... you're right when you say I want to keep some of that ugly stuff out-- or at the very least, I'd want to make it very clear that if anybody did go for that, they're terrible people, they should regret what they just chose to do, and I'll damn well moralize on that matter. Also, I'm just not sure if heresies are really a needed thing right now.