Keep pushin' it Square&Compas. I'd like to know how we know the guy left the scene. Is it in the police report? It seems like it'd be a massive failure if he weren't charged. Isn't this a "hit and run?"
I keep thinking this guy should be charged with road rage. It seems like there are a half dozen witnesses that he was losing his temper and either he's unfit to drive or he was too angry at the time to successfully complete the pass.
I think you can pull multiple trailers in Iowa. According to some RV site I found on the web they allow it if your total length is under 70' for RV's (I doubt it's different for pickups).