Last year I planned on biking the San Juan Islands and posted here too. I ended up doing the trip and documenting it here on Yahoo trips
I had a Garmin forerunner and recorded my entire route.
Don't worry about not having a campground. I went the week before the 4th of July, the busiest time, and camped in the biker camping spots that are first come first serve. I didn't have any problem finding a campsite. As long as you have good weather this trip is amazing. Feel free to contact me if you need any information. I'm planning on doing this trip again this summer.