The R. J. Reynolds State Wildlife Refuge takes up the north half. Only about 400 acres on the island remain in private ownership. Most of that is in the tiny community of Hog Hammock, the 70-some residents of which are the descendants of slaves brought to Sapelo in the early 1800s to work the plantations. You won't be staying at a Hilton, you understand, but these places are clean, tidy, comfortable, and inexpensive. Nothing about Sapelo Island is commercialized.
Transportation is by foot, bicycle, or hitchhiking.
You'll probably be surprised to see the Reynolds Mansion, the opulent former home of R. J. Reynolds, the tobacco heir. Reynolds bought the island in the 1930s and protected it from development through the 1960s, when primary ownership was transferred to the State of Georgia. Indoor pool privileges and all meals are included. If you can't stay on the island overnight, take the half-day tour. That includes the ferry ride to and from the island, a bus ride through Hog Hammock and the research facilities, and a walk-through of the Reynolds Mansion.