I second the Wilfred idea
We have done this before, 4 people [mix of friends, relatives] stayed for a week, never been before. We arranged a tour with Wilfred - so 6 total, we gave Wilfred a rough timetable. Worked well. Shopping in Marigot, stopped at Dreams, Grand Case walk around and bverage, lunch stop at Orient for a couple of hrs. We gave Wilfred a time to pick us up after lunch, then off we went. He could drop you in P'burg for your boat and maybe some last minute shopping. Reduces the stress, no worries parking a large van and you can have a drink with lunch

I understand it will cost more, but the benefits would outway the cost for me
J&B