Hi TP - be sure to check the Sunday schedule and call to see if anything is actually running. I ran into this about 5 weeks ago and nothing was running from VG - water taxis did not want to make the long run, and charter flights were not an option as I did not plan far enough in advance. No ferries on Sunday from VG (at least that's what is was then). We actually did a Saturday ferry to RT and Jason and Tiffany took great care of us staying at Coconut Breeze Villas in Cane Garden Bay - made the Roadtown/STT trip on Sunday fine. I've done land based VG many times (including your place) and probably never left on a Sunday as I was caught out with no options.
David