"the illegality of charging crew " Nah, by definition "crew" are paid hands, and that can create all kinds of fun under international laws. What we call crew on a round-the-beer-cans race, isn't "crew" in the same way.
If you are paying someone else to sail with them, that's probably a charter or other business arrangement tolling a whole other set of commercial laws. (Starting with their insurance being void unless it is comercial insurance.)
It was only in the late(?) 80's that the USCG loosened their collars about "renumeration" from passengers. Before they made the new policies formal, if you took a couple of friends out for the day and they bought dinner and fuel--that was deemed "compensation" and illegal unless you were a licensed captain!