Eastern Oregon is a big piece of real estate...can you be more specific?
The better the weather, the quicker the SP's fill up. Lots of us retired folk head for the coast day after Labour Day. I would think that actually getting a spot will not be big deal, but it might not be the 'best spot'.
You are going north to south, I hope. That coastal highway is a hazard if pulling left out of pull-offs to get back into traffic. Everyone accelerates when they see an RV trying to cross back over..mind you, being from Alberta, you'd fit right in. :B
The eating is fabulous...the views more fabulous. If you get as far a Brookings, book into the city owned site down by Coast Guard and pay the extra to get a front row spot.
Gary Haupt