As long as you don't go through Oregon, you can have your handgun loaded in the vehicle and/or concealed on your person, or open carry. Your Washington permit is good in both Idaho and Utah and all three states are also open carry states (Utah loaded only with a permit, which you have). It probably would not be a good idea to open carry outside Washington, though, because if you are within 1000 feet of a school outside Washington, you will violate Federal law by being in possession of a loaded firearm.