Laws vary from state to state, sometimes drastically.. and are subject to change without much if any notice, so the safe bet is just to call your local Highway Patrol and tell them what you got, where you're going with it, and if that's cool.
Just because some other guy didn't get popped doing the same thing doesn't mean it's legal in your state.. it just means a cop didn't catch him doing it, or had better things to do than hassle him about it.
Also keep in mind some things that are legal on a state highway, are illegal on county or city maintained roads or vice versa.
