Not sure but don't you have to have it inspected before you can put it on the road? I would think that one that size would cause some concern for your insurance carrier also. They may charge you more to insure it, or not insure it at all.
Here you have to show that a lic. welder performed the work, take it to the Hwy Patrol station have them inspect it. If it passes thay will give you a form to take to the DMV to get tags and a title. Thats the legal way lol.