RCW 46.37.080

Those sections of this chapter which follow immediately, including RCW 46.37.090, 46.37.100, 46.37.110, 46.37.120, and 46.37.130, relating to clearance lamps, marker lamps, and reflectors, shall apply as stated in said sections to vehicles of the type therein enumerated, namely buses, trucks, truck tractors, and trailers, semitrailers, and pole trailers, respectively, when operated upon any highway, and said vehicles shall be equipped as required and all lamp equipment required shall be lighted at the times mentioned in RCW 46.37.020. For purposes of the sections enumerated above, a camper, when mounted upon a motor vehicle, shall be considered part of the permanent structure of that motor vehicle.