Yes Marigot Bay is an excellent anchorage. You will find a accessible dinghy dock, Super U grocery store a 10 min walk away, excellent bakeries, ATMS etc. Also a good selection of restaurants in which to choose.

Clearing in is easy and a short walk from the dinghy dock, its is in a building across the road from the Port Louis marina - before you see the bistro O Plongeoir. Ask Customs at the ferry terminal and they will give you directions to walk there. In addition it will be far more convenient and cost effective to clear in and cruise on the French side. No bridge times to wait for openings and cruising permit far cheaper than on the Dutch side. In fact I prefer all anchorages on the French side versus Dutch side.

Enjoy St. Martin, it is a fabulous place to explore!