I just did Hilton Head recently, we had a rental and were doing city stops in Atlanta, Charleston and ended with 3 days in HHH.

I did AA ORD-ATL and then did a one way flight on DL from SAV-ATL to catch back up with my return in ATL. Oneways from SAV-ATL were $54 back in Feb.

HHH is a hard place to get to on AA, better off doing UA roundtrip into SAV.