The Washington State Highway Patrol have portable scales they haul around in their SUV patrol cars. They look like boards of wood. They can weigh you right on the side of the road - multiple axle vehicles, no problem. The troopers know the various tractor sizes and what they weigh. When they see a 12,000 lb Kubota being pulled by a 1-ton truck, they're getting pulled over and asked for their CDL. If no CDL, they're getting weighed. And when caught pulling a trailered load exceeding 10,000 pounds without a CDL, the ticket is 5 grand. The GVRW rating of the vehicle is completely irrelevant. It doesn't matter if your 1-ton diesel dodge is rated to pull 26,000, and your trailer is rated to pull 14,000. It doesn't matter how much your trailer is titled and/or registered to tow. It doesn't matter if you've got trailer surge brakes, electric brakes, air brakes, etc. You MUST have a Class-A CDL if you're pulling one pound over 10,000 lbs on a public roadway.
Naturally one might challenge said $5,000 dollar ticket in court. In Kitsap & Mason County the judge will typically agree to cut the ticket in half (pay only $2,500) if the person also obtains his/her CDL. Last time I checked the cost to obtain a non-hazmat CDL in Washington State was $4,600 (school classroom & driving fees). The hazmat endorsement was a few hundred dollars extra.
Again, the WA State Patrol is all over this issue. On any given day about half the people attending CDL school in western Washington are doing so because they're fighting a $5,000 dollar ticket (for pulling over 10k with no CDL).
Troopers will also stop and weigh 10 yard dump trucks whenever they can see the load from their car (aka the mound of crushed basalt rock visible from the SUV's driver's seat is a pretty good indication the 10 yard dump is overloaded). The troopers in possession of these mobile scales like to hang out around the rural highways - where there's no weigh stations between the quarries & the customers. And lots of non-CDL drivers hauling tractors, loaders, mini-excavators (over 10-k) with their 3/4 & 1-ton trucks.