I see this as a trial run on the RV lifestyle if "first RV trip" means first ever. I would leave off Olympic NP and WA's 101 and just do the OR coast. Assuming this trial run goes well, are you looking at buying an RV? If so then 7 days and fewer miles will give you a feel for this sport. Have fun, do not over plan it as one of the joys of a self contained RV is how flexible you can be. In May you will not need reservations, even at ocean front sites.
PS: Welcome to the forums... usually a lot of good free advice here. Also a lot of info hidden in the Advanced Search box above.
