Every state I’m familiar with specifies you must be in the field hunting, unless it is a check station. Everyone going to or coming hunting has to stop at these.
Washington regs don't seem too. That's why the easy answer is just comply and don't break the law!
Exhibit of License, Permits,
Stamps, Tags, and Wildlife
You are required to show a license, tag or permit,
or display wildlife taken when asked to by a Fish
and Wildlife officer or other enforcement officer.
You are also required to comply with the directions
of WDFW personnel related to the collection
of sampling data and/or material from wildlife.
Fish and Wildlife Check Stations
Any hunter may be directed to stop at WDFW
check stations and produce wildlife in their possession.
Fish and Wildlife Officers may stop any person
involved in a hunting or fishing activity for the
purpose of inspecting hunting and fishing equipment,
licenses, tags, or catch record cards and to
inspect all fish and wildlife in their possession.