starting on the island is good. Avoid as much of the crowds as you can and you should have a good ride.
I remember being terrified going up a slow long hill because there were people in front of me, lots of them; some were slowing down. Would someone stop directly in front of me?

this had already happened a few years before when we did this ride on a tandem (hint; i don't think this is a good tandem ride unless you do it a different day!)
a lady on a sparkly brand new bike did not know how to shift her bike into a climbing gear. She stopped and got off her bike in the middle of the road. We ran over her.
(she lived)
we had no way to stop in time. So be very defensive, careful, and legal.
good luck.
I really enjoyed this ride on my regular bike, except boy was I tired out at the end!