Kevin, I'm on the last chapter of the book on South Carolina I quoted previously. Whenever I get it finished and I have the time, I'll create some threads.
The common denominator between the planter class and yeoman farmer was Democratic Republican ideals of land ownership, and self-sufficiency. Slavery enhanced those ideals by eliminating a white laboring class. There were no conflicts between labor and capital in South Carolina and no close attachment to national political parties that tended to divide a state, undermine it's unity and weaken it's voice in national politics. For such a small state, South Carolina had a huge voice in national politics because of that unity.