You can look at this pamphlet -
And also look here:
The second link contains info about the cities that ban loaded open carry. If you have a Oregon permit then itexempts you from thelocal ordinances.
To my knowledge, there are no restrictions in the Mt Hood area. Be mindful of the reservations as they have their own laws. As with anywhere, if it's private property, they can ask you to leave and if you refuse you can be charged with trespassing.