ANother issue I see, is if you have a what I am seeing as a "CAR" plate for your truck, and you show up in say washington, loaded at 20 some odd thousand lbs gcw. My state may say you are not paying your share of the load tax, and cite you for being over loaded per your registration. ALL owners of pickups here have a truck plate, be it private or commercial. WE ALL buy in 2000 lbs increments. The I am over my paid for license is an infraction, where I am over or UNDER the manufacture limits! My PAID for license is king, up to the federal bridge law limits.
With a million or so pickups in some states, with a 10K plate at about $50 for the tonnage part, I am surprised more states are not adding this to you plate fee! I paid an extra 120 or so for my now sold 05 dually as a month ago, my c2500 is around $60 as I have an 8K plate. So I would be illegal running down the road at the door sticker of 8600, or 6K on the rear and or 3800 on the front. I could license it for 10K at an extra $10......Heck, I could go to around 18K and still be legal running down the road. BUT, an LEO I am sure would get me off the road if I weighed 18K with some infraction other than weight!
But, if you do have to cross the scales in Wa, with a car plate, and this state WAS enforcing truck plates on ALL rigs. you would probably be told to unhook your trailer, go get a registration that is valid for the what you are doing before being allowed to leave the weigh scale with your RV trailer. If a MH, and it has car tags per say, ala a bus conversion, you would probably be allowed to leave with your towed rig if you have one, and get an appropriate plate.....or they might be able to sell you one at the scale shack........
Then I could see story's of folks feeling like they were strip searched, bent over forward, reamed a bit etc etc.......
The chance of one getting pulled over in a scale with an rv personal use, is probably 1 in a very large number, ie a 1 followed by a million zero's.......I will not say none, because as soon as I say none, someone WILL get pulled over and have there wallet lightened for being over a paid for license tag!
marty