I agree. I've gone though Portland a few times. Twice was early Sunday morning and had no problems. Once was a weekday at 4 PM and we wound up crawling. The previously mentioned version is the best bet. When you follow the Columbia River to get to Astoria you have two options. You can travel the Oregon side or the Washington side. Hwy 30 in Oregon is the most RV friendly. The Washington routes are narrower and have more small towns to go through.
Mark & Leann Quasius
2016 Cornerstone 45A
2007 Allegro Bus 42QRP (Sold)
2012 Jeep Wrangler Unlimited - Rubicon