I dont know about marinas that would attract attention but I would advertise here on this site, on craiglist in Seattle , bellingham and Portland. State in your add that you will be available to show the boat by appointment at which ever marina you choose.Then come to the pot luck and have the boat on the trailer maybe?
See if the factory or the factories dealer will let you post a flyer at their booth, never hurts to ask. You could also try and be first to the parking lot in the mornings of the show and have a large for sale flyer posted on a board in the back of the truck. I saw a guy do that for his river sled at the Monroe sports men show a few years back. fast signs will print anything you want on a water proof sign board for fairly cheap. Tap flyers up around the show, what they going to do to you? ask you to stop at most.