I would love that trip but for some less enthusiastic sailors it may be a bridge too far - make certain everyone is up to the trip. Antigua to St Martin only, it would be a real slog the other way as stated before. The cruising guides will tell you what you need to know about clearance requirements - expect to do a lot of it! I wouldn't plan to do too many exciting things on land, this is going to be more of a sailing trip if you only have 9 days.

As I recall Horizon would be the most flexible as they are already setup to do this. I noticed Dream Yacht charters has some one ways from various bases Dream Yacht One Ways so you might ask them about your dates. I have also seen some interesting offers from Latesail's SailOneWay program LateSail One Ways although they have nothing interesting right now in the Caribbean but it won't hurt to ask. I think many of these are basically repositioning trips so you'll probably be going the hard direction but I have seen a few over the years that looked interesting and some very good discounts but they usually don't give you much time to enjoy it. Don't know if you can add more days so you have more "enjoy" time on island or not.

The other thing of course is the weather you get. I've put myself in the position twice of having to go just to make a deadline. I wouldn't go if it was dangerous but the admiral struggles on long rough slogs, it wasn't the "vacation fun" I wanted her to have. So, now I try to keep a lid on pushing it and at least put a few days in the schedule to wait out unfavorable weather.