Look at Google maps satellite. Just to the end of Man-O-War Cay is a large white-ish area on the map. There’s a huge sandbar that emerges at low tide. You can take a Minn’s boat there. Be sure to time your arrival there. At low tide you can anchor a boat near the edge, get out and walk all over.
Another place to walk on sandbars is the opposite end of Great Exuma. Follow the main road all the way to the far north west end past what Google maps labels as Rolleville. Do not take the left turn towards Barreterre. You will see a place where the main road turns sharply to the right and then ends at the water. Right where the road is curving to the right there is a huge sandbar on the left side of the road. You can see the white area on satellite. You can park your car right along the water there and walk quite far out. Again, aim for low tide. This would be a good day to visit Big D’s Conch Spot, although, the last time I was there, the Conch Spot was closed, and they did not know when it would reopen.