For those still seeking data on ancestors who were enslaved, or their descendants, on or near Bonny Hall Plantation, you can now find about 200 new headstone photographs on Find A Grave's page for Bonny Hall Cemetery in Beaufort County, South Carolina:https://www.findagrave.com/cgi-bin/fg.cgi?page=cr&CRid=2...
I photographed the gravestone of one man named Prince who died in 1858. I believe everything else was more recent. People with the surname Fields have the largest number of graves at the site.
Until November 2017, I'll be living about 30 minutes from Bonny Hall and happy to try to locate and photograph any related landmarks or genealogical evidence of which you're aware. Email me at firstname.lastname@example.org
The information available online didn't satisfy my curiosity, either. For a 500-word briefing on the cemetery location, you can see my blogpost:https://robinmizell.wordpress.com/2017/07/04/independence/
Kimberly Singleton, I uploaded a photograph of your great-grandfather's grave. You can download the image from Find A Grave or email me for a copy if you don't already have one.