I can't imagine that they'd let you tie up to the dock for a few hours on FMP night. What would you do afterwards? As a charter boat, you're not going to be allowed to go and pickup a ball over at Marina Cay afterwards, because it'll be dark.

Getting a slip at Scrub and using their ferry is the way to go.

In 2015, I let the FMP govern my whole itinerary. I wish that I had not. IMO, it wasn't worth it. The FMP experience was, meh.