We usually stop in Nassau to fuel up and then head on. Have bonefished lots of places in Bahamas but never on Great Providence. If you have a car the south side of the island towards the west has a bay labled bonefish bay on the charts. Good chance of finding some wadeable areas. Recommend a visit to google earth. We have used it successfully on many different islands to not only find flats that likely hold fish, but also access to that area, either by boat or vehicle. Look for areas that show very white, they are most likely harder walkable bottom and also likely to go dry at low tide.