Just switch to the +1 standard time. WA can switch to MST, which is equivalent to PDT.

It still requires federal approval, but from Sec Transit instead of Congress

You're saying the federal government granted blanket authorization to switch to the one? So the only reason states wait on authorization is merely obtusely insisting on the wrong choice? (In addition to being impotent.) The more I learn about this issue the more things I find to be angry about.