I don't know anyone who has done this before, but I know they used to have a boat that went over to Isla Mujeres for transport and they used the Moon Palace dock. When my FI and I were deciding where to book, the one thing with Palace that he really liked was the option that they used to have to do the sunset cruise with a wedding package. Unfortunetly, they don't do this one anymore & it was only out of Isla Mujeres (which we couldn't stay at because we have kids coming).
My travel agent said she spoke to someone when we originally booked about the possibility of renting a boat for after the wedding and using the dock. She said they'd have to check into it but it should be a good possibility, only thing is we'd have to pay out of pocket to the boat company (which I was already expecting to do). Like most everything else though, we booked back in October and I still don't have information one way or another for using thier dock! I haven't seen the catamaran rental on trip advisor, I'll have to check it out. Ideally, we wanted to do a sunset cruise after the wedding and before dinner, but I don't think there will be enough time if everyone has to get on a bus to get to the boat. Ahh, so much to figure out! But I'm so glad there's someone else looking into this as well, I thought I was alone on the idea!