We see that you can go either into Anacortes or cut across the island with about the same distance to the ferry. Any comments on the lower road? Hilly? Into Anacortes is a known, the other route i have never been across.
I live in Anacortes near the ferry; give me more information on your question -- highways 20 and 536 both come across the Skagit Valley to the ferry. If you'd like to use my direct email it is: email@example.com
We did the ride a few weeks ago. The route across Campbell Lake road is ok, but a little hilly, and not a lot of shoulder up the west side to the ferry terminal. On the other hand, Highway 20 is not very pleasant either.