There are MULTIPLE places that Sanibel police will hide on the causeway blvd once you are actually ON Sanibel. Times when you’ll spy said cops vary depending on the days (on weekends from around 1AM to light. Weekdays vary). It is good and common practice to slow down to the speed limit of that stretch (30mph) as soon as you get to the end of the bridge or turn onto the road from the island.