I live in this area and do a lot of fishing at WDFW sites at times. For a lot of them I don’t think camping is allowed and I don’t think there is enough room on the lands to just walk out and find good camping spots. It also depends on the game Warden. Some are cool and others are totally not-cool. Also, many of the areas shown on your map are rivers, swamps, wetlands, etc. They are not even completely accessible.
It can be difficult to find any land on this side of Washington State that isn’t federal land where one can camp legally.
You would have better luck checking out one of the Overlanding Map websites that has interactive maps of places found where they can post up and camp in strange spots.