Check out this site if you haven't done already. Pretty informative.
http://www.bobthecamper.com/index.html
We stayed in Kalaloch in E12 with our 34ft trailer and EX, aboot 53ft oal. But needed to park truck at angle to stay off road. Water and facilities right next to the site, but not a problem. Pretty quiet when we were there. Dump station is good and on road into the north section. Didn't spend time in the lower (S) sites, they were closed when we were there.
Be aware of narrow bridge on 101 crossing the Hoh River. Don't want to meet a log truck on the bridge!!!
