As long as your Michigan permit remains valid in Michigan, it will be valid in Washington, whether or not your are still a resident of Michigan. Washington also issues CPLs to non residents. Just go to the nearest police/sheriff department in Washington, pay $55.25 (it might have gone up), get fingerprinted and within 90 days they will mail you a CPL. Very simple application.
Anyone who says, "I support the 2nd amendment, BUT"... doesn't. Element of Surprise: a mythical element that many believe has the same affect upon criminals that Kryptonite has upon Superman.