1. You are out of state.
2. You have a "ladder rack" on the truck.
3. Sounds like you "carry a ladder to the work site for work"
4. Toolbox in the back.
5. 5th wheel hitch in back.
And, you think the cop is stupid for stopping you? Looks to me like he was doing his job!
Looks to me like you need DOT numbers! Ladder rack, with a ladder used for work, out of state, going to a job.
Sure sounds like a work vehicle to me, EVEN if it is registered as a private vehicle.
The USE of the vehicle is what is important, NOT how it is registered or owned.