Yep. That can get real touchy. I know that personally, on FB, it really irritates me when people put me on any kind of mailing list.
The only way I see around it, if you're doing it on FB, is to send individual emails to those you know -- that might be interested. That is: if you're going to use social media to announce it.
If you want help to do it through this website I'll be happy to do what I can to help you.
I have some pages and groups that I've started on Facebook that also are reasonably popular, that people in recovery have subscribed to, and you could post an announcement on those, too. That might help a little bit.
The other way to do it would be to physically get out there and announce it in meetings.
Best wishes! Sounds fun! If it wasn't so far away -- and I could make it, I'd like to attend!