Sorry about the late reply...I'll post an answer here in case someone else needs the answer... I believe Moran State Park  has some walk-in campsites that do not allow people to reserve... meaning that the first people to get there in person with their tent in hand get the campsite. Other places to camp on Orcas Island include West Beach Resort Doe Bay Resort , and Obstruction Pass State Park .

Another option is to go over to Orcas Island for the day and then return to a campground in Anacortes in the evening.

Did you end up coming to the skate park?

Here is a sweet camping  skating  orcas island video from the http://www.sk8rats.com gang... Orcas footage starts at 3:20.
[youtube]http://www.youtube.com/watch?v=920I0Z-1bV8&t=3m20s[/youtube]