How many days will you be on the boat. In a week there is more than enough to cover without taking the time to cross into the US and back. With 16 you may find your time or schedule always strained. With 16 most groups will be spending a lot of time herding the cats off and back onto the boat. Fewer stops with greater offers ashore may be the order of the day/week for a crew of 16. I would make sure I had a kayak or two to allow at least some to get off the boat on their own.
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