I'm not sure if you are looking for suggestions on just the north bound trip, or both.

On your trip south, I presume you also plan to view Cockspur Island, on the way to Tybee. Hunting Island is a very pretty setting, and is near Beaufort which is a wonderful old city.

While in the Oak Island area, have you seen the Prices Creek Light? Takes a ferry ride, but you may be able to work that into your travel plans.