i think muzzle load would be the way to go, since your hunting the rifle season you can use a scope and a sealed primer rifle that uses the 209 primer and jacketed bullets almost as good as rifle, but the reload time is longer.
Can't use 209 primer and jacketed bullets legally in WA, even during modern.
CP is right......there has been lots of discussion re: what is legal with ML. Basically, the RCW says if you use ML it must follow all the same rules as set for ML during ML season. It stinks.