With hired captains, check if you have the option for them to drop you off at West End on Day 5, and they return the boats to Roadtown. If so, then you have much better options for spending the last night moored or anchored out rather than at a hot, stuffy Roadtown marina.

With an 8:30 am drop-off I would plan to be in West End by 8 am to allow time to find a mooring, load the dinghy, and get ashore. With a sunrise departure you have plenty of time to arrive in West End by 8 am from several locations.

Cooper Island is 12nm (1h40m) and has a good restaurant and bar with lovely sunset views and nearby snorkeling at Cistern Rock.
Deadman's Bay at Peter Island is 9 nm (1h15m) and has a beautiful beach and very good dining at Peter Island Resort.

You might even be able to squeeze in a Day 4 afternoon snorkel at the Wreck of the Rhone (Salt Island) which is only 1.6nm~2.3nm from these anchorages.

If you want more secluded anchorages and will eat onboard, try White Bay on the south shore of Peter Island or Benures Bay / Soldier Bay / Privateer Bay at Norman Island.