I am not from WA so maybe take what I have to say with a grain of salt.
That being said I have harvested my fair share of public land turkeys in the east.
Wake up early and try to quietly walk through the woods listening for gobbles off
the roost. In Ky they like to roost along river edges or ridgetops in hardwood trees
(I don't know about WA)
Just burn a lot of boot leather (this is assuming of course that you have already
looked the area over on google maps, regular maps, etc.
Good luck.