Sorry, Gary - it appears I misunderstood your question, sounds like you are thinking of departing from St. Simon's, right?
Unfortunately, that involves a considerable amount of losing a lot of ground back out to the SE, that's the problem with going back out any of the Georgia Sounds heading north, and St. Simon's is the worst - involving the greatest distance heading SE before you can turn the corner headed N... And, you do not want to cut that corner headed N, by much, anyway...
I have not made this trip. I am wondering how much ground you are referring to that would be lost leaving from St. Simon's. How many miles before you can turn ne? Some of that distance is easterly so that would not be lost. It just doesn't look to me like a serious detour. It might add an hour or two to the trip at best. Is that a fair estimate? I am not trying to be contrary, just wondering about the choice. It might shorten the trip if weather is favorable and traveling inside is avoided.
Thanks for your experience.