I suggest that you ask your charter company their policies directly, but would highly discourage the southern entry to the Cays. This is more used by people with local knowledge. If you climb to the top of the hill on Mayreau and look at the Cays from the Church (highly recommended), you can see what it looks like. Mayreau is only about 2 miles long and I recommend you sail/motor the extra distance and follow the "normal" route and pass between Petit Rameau and Petit Bateau to enter..

The best/safest way to get to Petit Tabac is to arrange one of the boat boys to take you, weather permitting.