Washington is quite good on open carry. There are still a few police officers who don't care what the law is, but all departments have been pretty well educated. Washington has its share of anti-gun citizens but also a vibrant open carry movement so we are in pretty good shape. Negative incidents have become fairly uncommon other than a few misinformed people spouting off. Where you are going is not one of the major metropolitan areas so while I don't have any direct open carry experience on the island it should be pretty easy.
I am sure being a OCDO veteran you will check the WA forum for general WA info and laws. Be aware that WA laws on car carry are a bit weird - (without a CCW/CPL has to be unloaded) so be sure to check that out. There are no restaurant carry restrictions, but you are restricted from carrying in a bar (over 21 area). Private property no gun signs don't carry any weight other than the usual issues with private property rights, being asked to leave, and trespass issues if you don't, that seem to start L-O-N-G threads when ever it is brought up.
Getting a WA permit is easy.
We look forward to having you in WA!