Sounds like Festiva https://www.festivasailingvacations.com/ might be what you need. They've been doing sailing by the cabin for years. The format works well but of course you run the risk of your fellow crew members not being who you would choose to spend a week with, in very close company, for pretty much 24 hours a day. That's a risk you have to take.

There may be other options. I used to do BVI sailing vacations where people could book just by the cabin and my wife and I introduced many people from this forum to the joys of sailing but we have sold the boat so can't help. There was another forum member who used to do the same on his boat, but I believe he has also 'retired'.