I'm a DOT inspector...
If you go out of state (Interstate commerce) and depending on the CGVWR (truck & chipper combined) you will need to look at annual safety inspections. My books are at work, but I think 10,000 combined is the starting point.
Intrastate (your state only) will have different rules. A chipper is special mobile equipment and SHOULD meet the same requirements as a trailer (lights and brakes). Weight is the issue.
That all being said, if you are pulling junk down the road and do not have lights, plus your coupler fails and your chipper runs off and smashes a mini van with mom & kids, you will be hung out to dry!
Please ensure your tow rig, coupler, tires, brakes and lights along with the chippers coupler, tires, brakes and lights meet federal DOT standards so you don't kill my wife and kid. Be professonal with ALL of your equipment.
If you can't turn a wrench, bring it to someone who can.
Be Safe.
Bob