In the state of Ohio... I talked to the head honcho several years ago. I had a '6' commercial plate on my Ford Ranger but towed a trailer so the GCVW was just over 10,000lbs. He told me if I got stopped it would be over $2800. fine. He recommended me getting a '10' plate so my fine would be just over $250 if I got stopped. He also said if I went up to a '14', the next plate up I would have to have a DOT number and a commercial gas tax sticker on the truck plus a log book.
I asked him how the landscapers were getting around all this to which he replied, "we don't enforce it much yet but when we do there will be lots of landscapers hurting lots."
His final advice? "Just get a '10' plate so if you do get stopped it will only be a small fine and we don't stop Rangers anyway." Then a chuckle. Worked for me!
The rules have changed since so I changed my CDL to an intrastate instead of interstate and understand I don't need a medical but I really don't care anymore as my "trucking" days are over except for my 5th wheel camper behind my Ranger. Happy camping!