Let's not make this more complicated than it needs to be.

Scooby takes a ball in Great Harbor, Jost. Late crew contract with a water taxi for passage from St. Thomas to Great Harbor. Late crew checks in at C&I with de facto Cap'n of Scooby right there and all is well.

IF for some reason C&I in GH is closed, then the late crew checks in the next morning ASAP, and all is well with that, too. Great Harbor is likely the best and easiest C&I point to do this in the entire territory.