I agree with FatTire.
My Son works for a Tow Service. In Missouri it's 4 chains required to secure the tractor. For example, driver's side front chain binds to the passenger side front of the trailer. Makes two X's, one at each end. Then the attachments are required to be chained down to the trailer floor to prevent bouncing. The clevis on the drawbar is definitely a no-go.
For me, I don't worry about it so much. But for legal, I'd chain it down and then visit the local State Operated Hiway Scales. They'll tell you how you are doing. Take plenty of extra chains/binders.