We stay at a RV part 8 miles south of Sea Side at Cannon beach RV resort, all the pads are paved, very good power 50/30, good water pressure, really nice folks and has many large sites and a number of pull thoughts ...
You can walk into the south end of Cannon beach from the part or if you really like to hike downtown..
We have stated at the Thousand Trails RV park in Sea Side, it has paved roads, stone and sand sites which are not that level, wifi is the worst, have to go to club house to use it. For a membership park I think it's below average and I would not pay for a membership. We stayed because of friends who had a membership, we paid more than Cannon beach which was 10 times nicer ..
We also like Rockaway OR Beach RV Resort, but is very small and hard to get into. They do have some other RV parks there, look like lots of room but they are not on the water like the RV resort.
Safe travels