Hey there.
I've been on the Cooper a number of times now, and I've sort of "apprenticed" with an experienced guide there. My wife and I live in North Georgia and are thinking about moving to the Georgia Coast in a year or two, and I'd like to start a charter service for fossil diving the river.
Like the Cooper, the St. Mary has "hot spots" that change from year to year. To my knowledge, these have not been mapped by anyone, and finding the gravel beds that throw fossils is a painstaking process that can take a long time.
I've been boat shopping for a little while now and will probably not buy this year but next; at that time I'll begin spending real time on the river and will need help. Contact me by private message if you'd be interested in working something out. It wouldn't be for pay, but free diving in exchange for helping me on the boat and making dives to identify and mark good fossil beds.
To my knowledge there isn't anyone offering a regular charter service on the St. Mary but I have also seen very good quality fossils and artifacts that have come from the river.
Let me know if you're interested.