It's a packed agenda to fit STT, STJ, STX, and SVI into a 10 day charter. Will you be off the dock by early afternoon on April 1st? I'm calling that Day 1. Who are you chartering with?

Day 1 - St John north shore (Scott Beach, Francis/Maho, Hawksnest, or Leinster)
Day 2 - St John south shore (1st choice - Salt Pond Bay, 2nd - Little Lameshur, 3rd - Great Lameshur)
Day 3 - Dawn sail to Buck Island (~5 hr). Late afternoon sail to Christiansted
Day 4 - Rent car from Centerline Car Rentals near waterfront boardwalk and tour St Croix (Point Udall is a highlight). Walking tour of Fort Christiansted. Instead of driving tour, you could head to the numerous dive sites around STX. If back to boat by ~2pm, you could sail to Frederiksted (16nm, ~2.5 hr). The pier there is an excellent nightime dive.
Day 5 - Dawn sail to Ensenada Honda, Culebra (49nm from Christiansted, 6am~1pm.43nm from Frederiksted ). Clear in via CBP ROAM app (confirm your boat has the CBP User Fee Decal for 2022). Taxi to Playa Flamenco
Day 6 - Early AM to Bahia Tortuga, Culebrita (7nm, 1hr). Late afternoon - overnight at Bahia Tortuga or move to Bahia de Almodovar (4nm, 40min)
Day 7 - Early AM to Magens Bay (19nm from Bahia Tortuga, 23nm from Bahia de Almodovar, 3~4 hrs)
Day 8 - St John, Lind Point or Honeymoon Beach - dinghy ro Cruz Bay for sightseeing, shopping at Mongoose Junction, visit NPS museum, lunch.
Day 9 - St John north or south shore
Day 10 - St John to STT marina