McKenzie Pass in Oregon (Hwy 242) is closed to trailers due to switchbacks. I have towed over plenty of roads in Oregon that wouldn't be advisable due to 10 mph turns and single lane bridges. These roads are out in the sticks and are lightly traveled. Large trucks service the towns out there so you can make it.
Don't know the height of your rig but I would stay off of Washington 14 between Vancouver and Bingen. There are some low tunnels on that stretch. Extremely beautiful road but you can enjoy the gorge almost as much from the freeway on the Oregon side.