Yup that's the one to stay off of with a trailer. Main route of 101 is a breeze.
Other tidbits, mostly about the Central Coast.
Yachats (yah hots) has diesel. Reedsport, Florence, and the north side of Tillamook have convenient fuel stations.
Waldport is a great and beautiful town, south of Newport, that most people just drive through. Grand Central is a great pizza place and there is a nice icecream shop across the road. There is also a very convenient and clean municipal dump station; costs three dollars; it is the last left on the south side of town on Star St. by the RV park. South of town Gov. Patterson is a very quite day use beach with easy and close parking.
South of Lincoln City (just drive on through there if you want to avoid the crowds) is Gleneden Beach. There is nice beach access to one of the best places to hunt aggots (at low tide) and there is also the Side Door cafe. Speaking of tides, the iPhone app High Tode is a useful tool while on the coast.
Rogue Brewery in South Beach is a nice place for lunch and they have a big parking lot. Old Town Newport is great, but parking is tight and limited; not trailer friendly.
My favorite campgrounds are all state run, they are:
South Beach in Newport
Bullards Beach, Bandon
Sutton, Reedsport
Beverly Beach, north of Newport is not very private and a bit overhyped. But if you can get a spot closest to the beach it is pretty convenient.
Bandon Creamery is a yummy stop in an overall cool town.
Tillamook Creamery has trailer parking, but it may be full, and you will have a bit of a walk.
Tillamook County runs a campground, Bayview Jetty Park, that is not too private but has full hookups and easy access to Garibaldy and Rockaway. The steam train ride out of Rockaway is pretty cool.
I think I will keep my last couple of secrets