As others have noted most campgrounds and RV parks along the path of totality are sold out and many have waiting lists.
Camping sites in Oregon State Parks, along the path of totality, were sold out within an hour of becoming available. In like manner, most (if not all) private campgrounds and RV Parks are also sold out with some having waiting lists available to fill possible cancellations.
The Oregon Museum of Science and Industry (OMSI) is hosting a
Solar Eclipse Viewing Party at the Oregon State Fairgrounds in Salem. They have RV sites available (as of today) but they are without hookups. Information can be found here.
Eclipse Camping at Oregon State Fairgrounds in SalemWe're avid amateur astronomers and started working on this months ago. We have reservations at two campgrounds and are on the waiting list for third. For the time being, we've settled for a site in an RV park at the fairgrounds in Corvallis, OR where we have family. We'd rather be on the coast and are on the waiting list for the Premier RV Resort in Lincoln City. (We started at #42 on the waiting list and as of yesterday, 2/7, had moved to #37. The park staff noted that smaller RV's, like ours, are moving up the list faster than longer ones.)