License plate on Truck? or camper (with overhang)?

I can't believe it but now I think I'm actually glad WA puts license plates on campers.
Here, its simple; truck plate goes on truck, camper plate on camper.
I figure it's the same as pulling a trailer. You can't see the truck plate then either but you can see the rear-most plate.
Ive never had that questioned in my 30 or so years of having pickup campers.