Also, that next week is the July 4th holiday.
Cammping will be very difficult to come by.
Lodging will be horribly expensive and practically unavailable.
Of the four islands, San Juan is the busiest.
Friday Harbor used to have a hostel - but the partying goes on all night.
There is a lovely campground on the west side of the island - availability?
Orcas is the next busiest and the state park is a good distance and uphill.
The state park does have hiker/biker camping and may not be full.
Lopez is my favorite - quiet but with village services - two campgrounds.
Both the state park and county campground accommodate cyclists.
(The beachside campsites at the state park are reserved months in advance -
The county park is a little more cyclist friendly.)
The village has a grocery and great bakery/cafe.
Shaw is the most remote island served by ferry.
There are NO commercial services on the island.
The small county park is likely to be filled.
If you want to go to one of the other islands beside San Juan -
You can take the Noon ferry all the way to Anacortes and backtrack.
A little more, but you can get situated by mid afternoon.