Did the walk from Great Harbor to Soggy Dollar Bar a few years ago. I did great. My wife had a bit of problem with the April sun the 10:00 am heat and the climb, BUT there were enough trees along the climb to pause and she could cool down. I just don't know if those trees are still there after Hurricane Irma and Maria.
We asked the manager of SandCastles/Soggy Dollar Bar, who was filling in the morning shift for the bartender, how we could go about contacting a cab for a ride back. She gave us a ride back since she was taking customers from Sandcastles to the ferry.
So yes, you can walk or cab to and from if you wish.