The name of the very good flat was the Barcadera, a locals public beach and dock area with huge piles of white sand (or salt?) just to the east on the south side near the Balashi brewery. You will want +/- 2 hrs around the low early morning or evening there, textbook tide situation. Baby Beach could be great across from the chair rental shack but once people show it's soupy and crowded. Dawn patrol or bust and it's a looong drive from the Divi.
Best jack fishing I found was at the trench near the lighthouse on the northwest tip, and the jailhouse beach near baby beach on the other end of the island.
Your best bet is to go up to the wreck at Malmok in the mornings and evenings and keep those Monomoy-trained eyes pinned for green backs. This is a place where true-color sunglasses are better than high-contrast for me anyway, because the color differentiation is the key to seeing these fish in coral. These oceanic bones are aggressive and not all that spooky compared to flats bones - especially since there are waves. I cast into a wave as it rolled over a fish's path and when the wave passed and cleared out a window my fly was descending into the sweet spot. A twitch or two and bang! off to the races but pay special attention to clearing the line over the coral as this is about the easiest spot to get cut off by a smart bonefish I have ever fished. I only landed two but on sand I would have landed several more on the day I hit them just right.
Note - the day before I was spotting lots of bones from horseback riding with my wife and father in law on the sailboarder's beach just north of the Divi. The next day I hit a bunch of them, and from that day on there were no bones to be seen there when I could sneak away. My theory is that these oceanic bones roam the shoreline and could be anywhere as opposed to the flats and mangrove dwellers who have the compulsion to return to the same spots on queue based on tide activity.
The guy who lives right across the street from the wreck beach says the tails come out in the evening calm regularly, but that time is usually reserved for shirt and tie dining with the family and I never got to try it.
BTW there are also tunoids like true albacore in the rips just offshore. The boats near the officers club at baby beach are local fishermen who handline for wahoo and albacore. They told me a piece of shrimp fished along the beach at night would produce bones galore. Never tried that either although it would be pretty interesting to try right on the Divi beach.
Good luck in March.