Thanks for posting on the message board... you are in luck and there is public storage available at the ferry landing in Friday Harbor.  When you get off of the ferry you will see a restaurant right in front of you called "Friday's crab House"... there is a man who sells barbecued and raw oysters right in front of this restaurant who has a daily storage business.  He charges three dollars per bag.  I'm not sure if he offers overnight storage... can you please ask him when you are down there and let us know?

I totally recommend the oysters!  You can also buy them yourself from Wescott Bay Oyster Farm  (  near Roche Harbor  ).  Enjoy your time in the islands!