RCW 46.85.050

An agreement or arrangement entered into, or a declaration issued under the authority of chapter 46.87 RCW or this chapter may contain provisions authorizing the registration or licensing in another jurisdiction of vehicles located in or operated from a base in such other jurisdiction which vehicles otherwise would be required to be registered or licensed in this state; and in such event the exemptions, benefits, and privileges extended by such agreement, arrangement, or declaration shall apply to such vehicles, when properly licensed or registered in such base jurisdiction.