While not in a commercial plate state for vans and trucks (pickups), I did see a few years ago that Louisiana was all commercial. I remember asking a driver from there if he had problems on the road, he said he never did as everyone understood that the basic pickup wasn't going to be overweight or needing a CDL license.
Here's what Maine says, and many states use about the same language:
Why does my pick-up truck have commercial plates when I am not in commerce?
"In Maine, all vehicles over 6,000 pounds are registered by weight. This is true whether you are in business or are a private person. Any vehicle registering for a weight more than 6,000 lbs is given a commercial plate. "Commercial" is simply the name of the category of plate.
A pick-up truck can be registered as a passenger car, but then is limited to a weight of 6,000 lbs for vehicle and load. Many larger pick-up trucks weigh more than 6,000 lbs empty. These vehicles must register for a higher weight.
What weight should I use when I register my truck?
You should request enough weight to cover the truck, the truck's load, any trailer you might haul and the load on the trailer.
Do I have to stop at a truck check?
State law says that all vehicles subject to gross vehicle weight restrictions must stop at a truck check. Generally speaking, if you are in commerce and you weigh more than 10,001 lbs, or carry 15 or more passengers or carry hazmat, you must stop.
Do I need a DOT number?
Yes, if you are operating a vehicle in interstate commerce and the vehicle
has a gross vehicle weight rating or gross combination weight rating or gross vehicle weight or gross combination weight of 10,001 lbs whichever is greater or
is designed or used to transport more than 8 passengers (including the driver) for compensation or
is designed or used to transport more than 15 passengers, including the driver and is not used to transport passengers for compensation or
is used in transporting material found by the Secretary of Transportation to be hazardous.
Yes, if you are operating a vehicle in intrastate (in Maine only) commerce and the vehicle
has a registered gross weight of 10,001lbs or more or
is a truck with three or more axles on the powered unit, or
is a bus for hire that has been issued a Permit for Operation of Motorcoach Intrastate Carrier by the Bureau of Motor Vehicles"
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Notice that it's all about weight or using it for a living. No you, with a less than 10,000 private use vehicle, wouldn't stop at weigh stations...