I towed a
Smart Trailer with a couple of bikes on it for a few years, until I got tired of the hassle.
We passed through Illinois several times with no issues. We also traveled through, and stayed in, several other states that don't allow double towing. We were never stopped or even given funny looks by the LEO's.
Some people will tell you that you'll get stopped at a particular state's border, but they usually, almost always, are operating on hearsay. They have no actual experience with double towing with something like a Smart Trailer, or a swivel wheel trailer. My opinion is that the LEO's don't quite know what to think of them, so they just ignore them.
We just went and figured if we got stopped we'd deal with it then. We never got stopped so we never had to deal with it. You won't go to jail, you won't die because of it. It's kind of like the adult diapers: Just "Depends".
๐Whatever you do make sure you've got enough truck for the application.
Howard and Peggy
"Don't Panic"