During the summer, I think the boat launch area tends to almost as crowded as regular Alki Beach. I don't pay much attention to it 'cuz I don't have a boat, but I usually swing by there 2-3 times a month and I seldom notice open parking spaces... I think the lot will be really full at 3:00pm on a Sunday. Maybe I am wrong and there will be parking at the boat docks.
But I am open to meet wherever -- my suggestion is Alki Point, which is quieter and less busy, but parking will still be an issue somewhat, and it will be hard (if not impossible) to get the VXes all lined up no matter where we go down there. Perhaps we could meet at Alki Point (where parking is more likely), then drive over to the boat docks for a photo op if possible?