So nice to have first come/first serve campgrounds so close to Portland. I arrived around 2 on a Wednesday in August and grabbed one of 3 open sites. (There are group sites also that were FCFS, but they cost more.) 

I'd read about the hiking trail right outside the campground, but was super stoked to find a paved off-road bike trail. I took it 6 miles up to Venieto State Park.  Along the highway, but still very pretty. Waterfalls and great scenery!

Yes, you can hear the highway from the sites. Lots of trees, though and lots of privacy. No hook ups. Decent Verizon coverage.