Keep in mind that GVWR (Gross Vehicle Weight Rating) is the declared weight rating of the manufacturer and is found on the sticker (or plate) placed on the vehicle by the manufacturer, usually on the inside edge of the driver's door, or in the case of a Sprinter, on the side of the driver's seat. The GVWR can also be obtained from the DOT database using the vehicle's VIN if the sticker (or plate) is missing.
The GVW (Gross Vehicle Weight) is the amount the vehicle actually weighs.
The Department of Transportation, and the FMCSA (the Federal Motor Carrier Safety Administration, separate administration within the U.S. Department of Transportation) regulates Commercial Motor Vehicles (CMV) used in interstate commerce, and requires the drivers of CMVs to comply with the Hours of Service regulations.
Who Must Comply?
The DOT and FMCSA definition of a CMV can be
found here, in the US Code of Federal Regulations, Title 49, Section 390.5, and states:
Commercial motor vehicle means any self-propelled or towed motor vehicle used on a highway in interstate commerce to transport passengers or property when the vehicle—
(1) Has a gross vehicle weight rating or gross combination weight rating, or gross vehicle weight or gross combination weight, of 4,536 kg (10,001 pounds) or more, whichever is greater; or
(2) Is designed or used to transport more than 8 passengers (including the driver) for compensation; or
(3) Is designed or used to transport more than 15 passengers, including the driver, and is not used to transport passengers for compensation; or
(4) Is used in transporting material found by the Secretary of Transportation to be hazardous under 49 U.S.C. 5103 and transported in a quantity requiring placarding under regulations prescribed by the Secretary under 49 CFR, subtitle B, chapter I, subchapter C.
Some states have different or additional regulations for intrastate commerce, and Missouri is one of them, but they are actually less regulated than are the interstate regulations. You will find both interstate and intrastate regulations for vehicles registered in Missouri in this
MODOT PDF file, by scrolling down to the top of Page 7.
Notice that all of these definitions and regulations couldn't care less what weight your vehicle registration plate has stamped on it.
So their answer then became .. If you are registered for 12,000 you will have to do a log book.
Idiots. Next they'll probably tell you that you can't carry mouthwash with you in the van because it contains alcohol. <snort>