Unlike the other "fringe" groups I've covered in the past, this one is very controversial, so this post will be a work in progress as I find more information.
Reenacting American slavery through the Civil War has been a sensitive subject that a few intrepid individuals have done, but not enough to reflect it as common as it was in the South. It's painful history, but history we need to portray if we're to paint an accurate picture of slavery. Apart from making the news on rare occasion, we don't hear too much about it reenacted.
Stacy Roth has a great chapter in her book Past Into Present about a slave auction reenacted at Williamsburg - what though went into creating the scenario, what actually happened, the controversy that surrounded it, and the final outcome.
The San Jancinto reenactment in 2002 had a respectable contingent of slave reenactors, which makes me wonder if there are any organizations that do research and specialize in such impressions, or if it's one-time thing. The Somerset Place and Latta Plantation in NC have programs involving slaves that look interesting, and Sam Houston University has a presentation about Sam Houston's "unread" side that looks a bit humorous. On the serious side, Camp Cosby nearBirmingham, AL has a segment that gives 4th and 5th grade kids a taste of what it was to be a slave. I don't know if this is an entirely accurate take, but I'll allow anyone knows more about this program to make comment.
Mary Fears has written a book on reenacting slaves, Civil War and Living History Reenacting: About "People of Color" How to Begin, What to Wear, Why Reenact gives some practical viewpoints to consider when approaching slavery as a recreated part of the hobby. This article, copied from the from the LA Times about the living history program at Brattonsville, SC gives a picture of the pitfalls of presenting slavery in a "too positive" light, particularly if the historic place has a darker history in regards to slavery. Although Freetown's living history program takes place after the Civil War, their educational guide is something that is well worth looking through, anyone looking at doing living history presentations would benefit from it.