I haven't sailed the south shore of Cuba, but I have spent some time on the South coast between Cabo Cruz and Santiago. If you are planning to spend some time there on land, I highly recommend a couple of things. If you can pack aboard a couple of cheap
bicycles, you will be well served by them for inland adventure. I have cycled the road between Santiago and Cabo Cruz and it is a fantastic unspoiled coast for riding. Sometimes you ride for 2 hours on the paved (somewhat) road, and share the road with no cars!
The National park with Mt. Turquino (spelling?) is something I want to go back and hike.A guide can be hired inexpensively, and there is very basic accommodation available near the top.
If you can manage, plan on leaving the bikes there with some locals. You will be visiting one of the poorest provinces in cuba and leaving the bike is well appreciated. This act of goodwill will come back to you twofold, be sure.
Here, on the right, is a pic approaching Turquino from the West, typical of the terrain there.
I'm not sure about anchoring/marinas along that coast, may be a bit of a challenge. I don't recall
seeing a lot of options. There were a few boats anchored in Marea Del Portillo where I stayed, but I got in trouble while taking a rented resort kayak
out to visit a boat flying a Canadian flag. Decent anchorage though. On the left is a pic of the anchorage, zoom in and you can just see a boat anchored off the the right of the peak.
Best of luck Murtaig and Crew, enjoy!