Communicate with a Group of inaturalist users in an area

I’m trying to figure out a way to send messages to a core group (maybe 10 or 20) frequent inaturalist users in my area. I’ve thought of creating a project that only those people are members but I don’t think that seems like a good method. I thought of creating a group outside of inaturalist (like an email list) but just wonder if anyone else has tackled this. The reason for it would be to share information about keys to difficult species, to invite to an outing, ask questions. With a project I could create journal entries and people could responds. Just wondering if anyone has tried anything like this.