In the Boldt Decision each Tribes's U&A was defined and mapped. I am sure WDFW has a copy. Since then, Tribes have used the Courts to expand/contract U&A's. If the Skoks have some historical, archaeological data that has come to light then they would have a good case. The 1980s probably don't count, under Boldt, as where they fished historically.
Should be remembered that individual tribes had long-distance relationships with other tribes. The Yakimas and Nisquallys were close enough that the Yaks have (or had) U&A in Puget Sound. I recall that there were South Sound Tribes (can't remember which) that had strong ties with the Coast.