Check out Guavaberry Spring Bay. They are getting back together and can help you find what you need. The sargassum is not on the Sir Francis Drake Channel side on Virgin Gorda, but is on a few places on the Atlantic side, which you won't go to anyway. Spring Bay is our go to place. It is a short walk from the Baths and connects to other beaches such as Little Trunk and Valley Trunk. We were down for three weeks in May and had no mosquitos and a nice breeze. Enjoy!