Pan Fry,
I'd be supprised if you can't find info from ODFW about birds they have established in your area. There are little pockets here and there that have been transplanted. I can tell you from experience on the family ranch, once they take hold, they expand rapidly.
There are lots of turkeys on public land, mostly in more remote areas. Over in the Wallowa area there are a lot of birds and few hunters. Heck of a drive from here. I think scouting in the areas along I-5 fron Eugene south and talking to landowners would yeild better results. Most landowners who didn't allow hunting 10 yrs ago, now want them thinned out (like Grantspastor)
From waht I've seen, the "back yard birds" along I-5 are easier to fool than the "mountain birds" from national forest areas etc.
I recommend getting a couple with your shot gun, then trying the bow. I've done it both ways, (last 3 with bow

) and they both work.
I prefer the bow.
Good luck.
GRB