this list. You can loaded OC while camping, you can loaded OC in state and national forests. Hotel rooms are private property, so theoretically you could be asked to leave for any reason, but outside of that you can loaded OC in hotel rooms.
If you want to OC in any of the ban cities other than Portland, you can unloaded OC with full magazines on your side. Portland has an illegal law (because the state hasn't granted them authority to regulate magazines) that makes unlicensed carry of magazines with any ammo illegal. Your best bet is to lock your firearm in a fully enclosed container while in Portland, but you can unloaded OC with empty magazines or you can unloaded OC with full magazines if you feel like being a test case in court for the legality of the magazine ban.