Congrats on your five-year healthy milestone, here's to many more! I used to live on the southern Oregon coast around Gold Beach, and wetness is a fact of life. Drying your clothes in the RV may be a challenge, so you will need to figure out a good system for drying clothes within the RV to avoid musty smells or mildew. I lived in an RV in Bend to ski at Mt. Bachelor, and it was challenging to dry my snow clothes. I am sure you will figure it out.
When in Oregon, I went for a high end rain shell (Patagonia) with layers underneath (fleece or Smart wool long underwear). That way when the sun comes out but the wind is still chilly, you can shed a layer. Nice baggy rain pants are good. I prefer baggy since it makes it easier to get them on and off with the friction from pants underneath, preferably with ankle zippers so you can leave your shoes on when you take off the rain pants when the rain or drizzle is past.
Lots of good smart wool socks to keep your toes warm even when your shoes are damp or wet. I hope you have a great time, sounds like a great goal.