You may also want to check your exhaust riser drain hoses, on my LSV they are a short hose that comes off the front of the riser and are connected together by a garden hose type fitting. When I winterize I disconnect them at the garden hose fitting to drain and then reconnect in the spring.

On mine I also remove the small bolt in the exhaust at the very back wall on port side of the boat. I usually get a small amount of water out when I winterize, I leave the bolt out during the winter and re-install in the spring.