You can visit the state and openly carry, yes. You can have a firearm in your residence (even a temporary one [ie, tent, RV]). You can have one with you while engaged in hunting or any other lawful purpose, essentially.
Check ORS 166.250, which says, basically, that so long as you aren't otherwise prohibited from having/carrying a firearm, you can carry. Unless you have a CHL recognized by Oregon, it must be carried openly. It can be in your residence, even if that's temporary.
And ORS 166.260 adds that the prohibitions in 166.250 about carrying are tossed out the window if you end up using it and claiming an affirmative defense exception (as would be the case if justifiably using it for self-defense against attack).
You're also in possession of a Washington CHL. While not acknowledged in Oregon for concealed carry, it certainly marks you as a "good guy" to authorities, if push comes to shove.
So, I think you're good to go.
Enjoy the visit.