You will miss a lot if you stay on one side. I would suggest camping on the OR side in most places and then day-tripping to the Washington side.
If you are comfortable on twisty roads WA 14 is for you!
I-84 east out of Portland.
Just east is Rooster Rock and Multnomah Falls. There is stretches of the Old US 30 going both directions. Would be difficult going with the rig.
Across the Columbia you will see Cape Horn. WA 14 is very narrow around the cape. Farther east on WA side is Beacon Rock.
Great stops on either side at some the dams. There is campgrounds near each of the dams.
Near Plymouth, WA Umatilla, Or area is a great Corp park. Many wind surfers visit this area.
