I am in Seattle........ and I know where the Tri Cities are. I can see the green glow in the sky from the Hanford Nuclear site from West Seattle!! Here is my knowledge of some laws straight from one of Washington's finest State Patrol officers. I was pulled over on my CB750 a few months back for having my license plate mounted vertically. That is a no no, two mirrors is correct in Washington. He also told me my aftermarket bullet style blinkers were to small and that they need to be 18" apart per Washington RCW 87687 Blah Blah Blah. Plus..... the little stock reflectors on the forks needed to be put back on. I have to say it varies from cop to cop. I fixed the license plate but that was it. Left the blinkers alone. I ride with tons of guys who don't even have blinkers, and have open exhaust that you can hear from 2 miles away...... so I don't know. Just watch out for Johnny Law when he is having a bad day I guess.
I think what it all boils down to is just driving responsibly and hoping you don't get pulled over by a cop who is into motorcycles