You are a member of the best resource I've found. I am sure there are any number of people in King County that would be willing to show you when they process their own. In Whatcom County, there is a Co-Op that owns the equipment, and you rent it when you process. I will be doing my next batch...
A place I found is:
Lampaert Meats, Inc
17658 W Snoqualmie River Rd NE,
Duvall, WA 98019
425-788-1128
I am not sure that they are taking new clients.
Have you thought about processing them yourself?