In a CSA victory, the Sea Islands seem like something that'd be an open issue. For a number of years, freedmen had been governing themselves and engaging in productive economic activity. Given the geography of the islands, they seem like an area in which insurgency could work well too.
In a CSA victory, could "Geechee Republics" have emerged as de facto (and eventually de jure) entities along the coast? Possibly sponsored by the union.