Oh nice! I like the Bon EA idea
You might also want to consider that, from the little I've been able to find out, Bon was "demonized" to some extent, by the Buddhists. As in, originally, the Bon demons and spirits were just regular gods that were replaced and marginalized. Ofcourse, they apparently still appear as demons and spirits in the current Bon religion, so either option (good spirits or bad demons) is open to you.
I wish I could find out more about Bon, but there's not a whole lot on the internet, and I can't afford the bookstore right now. I might hit my local library and see if they can come up with anything. We have a Buddhist temple close by, too, but I haven't gone there yet.