Recall that Rachel is already committed to looking after her father, so she is unlikely to be interested in leaving Martinique. But I do remember trying to find ways to get Sabine Matton (from the "Help the Boatswain" side quest) and Virginie d'Espivant (from the "Girl Won in a Card Game" side quest) to become officers, without success. (Perhaps if you choose to hold Virginie for ransom rather than help her find her fiance, she could appear in the cargo hold the same as any other prisoner, then you could have the option of asking her to become an officer...)
As Pieter says, ideas are easy, getting someone to implement them is hard. Nobody is being paid for any of this work, so anybody who works on something is likely to work on what interests them (and hopefully the rest of us as well, but that's a happy coincidence). Personally, if I ever figure out how to add things to quests, I'll see about extending "Chronicles of Horatio Hornblower". Don't hold your breath waiting for me to learn enough to do that any time soon, though...
You can already... er... "interact" with governors' daughters once you've won them over with your charm.
The exact nature of the interaction is left to the imagination. It can be dancing if you like.