I'm not sure if the cargo bike in this picture is actually up to delivery everywhere in the USVI, but judging from the apparent slope it looks worth investigating.
The link attached to this article has a review of another electric cargo bike and eyeballing the slope, it has about 5 feet of rise for each 8 feet traveled, a slope seldom exceeded on St John. The bike reviewed features a commercially produced Currie electric bike with a 350 watt mid-drive motor that retails for over $4000; I think the St Thomas bike builder can create a cargo ebike with a Bafang mid-drive motor with twice the power, better adapted for the islands, for a lower price and with local support.