Best would be to sign some deal with the Department of Transportation, to mount some professional equipment, on their so-called DOTX measurement cars, which are often attached to Amtrak trains right behind the engine. Or perhaps even better would be an external rear mounted or even front mounted camera. Yes, right on the very back of the train, or on the very front of the train, without any glass in the way. Like Capturing side view whilst on a train - #9 by dave683 YouTube video.