I’ve heard of folks using the airporter shuttles as a way to get from the airport to towns near the trail.
If you’re going to White Pass, get a shuttle to Packwood and hitch the rest of the way. Will likely be spendy. Another way is to fly from Seattle to Yakima (see below for airline) and hitch up Hwy 12.
Getting to Stehekin from Seattle: Check into Greyhound to get to Chelan from down town Seattle. If the Dog doesn’t go to Chelan, there’s another bus line (drawing a blank on it right now) that goes over Stevens Pass. The other way would be to fly from Seattle to Wenatchee (Check out Alaska / Horizon Airlines) then catch the local transit system bus up to Chelan (check the web for details). From there, take the boat to Stehekin.
Token Civilian