Seven Feathers Truck & Travel Center

We parked in the well lit upper parking lot behind the fuel station overnight and yes it is a truck stop. In spite of the traffic in and out of the lot and fuel station it was relatively quiet and we had a good night. Added bonus is that it's convenient to the best price on diesel we found in Wa. or Oregon and right on I-5.
There is an RV specific overflow type lot across the freeway near the casino itself. We haven't stayed there but it looks like there'd be less traffic and noise for the light sleepers.

This is a truck stop! It is packed from one end to the other with enormous semis with their engines going. I was the only RV in a huge lot of trucks! If you find yourself here, leave and drive half a mile under the I5 to the casino where you can park with other RVs. It still is noisy from the highway, but at least you aren’t surrounded by trucks.

Exit 99 has a lot of overnight camping opportunities. This is one. (The other options are the rest area, the fancy RV park and then the north lot at the casino.)

Behind the travel center there are two areas. The lower area is right behind the travel center and usually fills with truckers. There is an area above this lot that is very large. This is where we overnighted with other RVer's and trucks. Access to this large lot be obtained behind the truck refuel area or off the road leading to the rest area and RV park.

There are trash cans, portable outhouses, good cell service and TV reception. There are also 110 power posts available. We had a very quiet night in this lot.