We lived about a mile inland from Saltwater SP in 1969/70. There is a LOT of airplane noise, as it's almost directly under the flight path for SeaTac airport. We used to reckon that, if someone had stowed away in a landing gear bay, the body would probably fall in our yard!
Airplanes are a good deal quieter nowadays. but it will still be noisy.
Also, the road going into the park from the gate is narrow and twisty. I don't think I'd want to tackle it in anything much longer than 28'.
Unfortunately for us RVers, property prices around Seattle make it very difficult to have low-cost RV parks. I'd be tempted to look across the Sound and go to the "Clink" by ferry.
Frank Damp -Anacortes, WA,(DW- Eileen)
ex-pat Brits (1968) and ex-RVers.