Yeah, but can Seattle catapult their cows over that range? I'm sure that they could fart in your general direction. Talk about a nasty Chinook... Well, if rural eastern WA were able to seceed, I'm wondering if Clark(Vancouver, the most conservative part of the Portland metro) and/or Cowlitz County would leave, too. That would give access to the Pacific, no locks on the Columbia south of there. Kinda sticky relying on a river, but its a start. What about Pacific, Wahkiakum, or Gray's Harbor Counties, primarily logger or Native American dominated? Any of those three would provide an excellent harbor location for a base.
Better stick to the river, only two types of folks in Pacific and Grays Harbor: Those who work in Indian Casinos and former loggers who are on government support (for the 20th year or so) because it keeps coming and they haven't been able to log for a generation (ever since the hippies came and started worshipping trees and spotted owls).