For us it's pretty easy. We arrive in STT at 1:27, catch the 2:30 ferry to RT. Check in at Sunsail is at 6:00. By then we have had time to do some lite provisioning and dinner. Our flight was half the price of flying into EIS. Depart at 3:45 the day after we return our charter without having to rush around. Just our experience, we have always chartered out of Tortola.