I have contemplated a "caboose-cam" few years ago but it never cam to fruition.
In order to make the camera non-obtrusive I thought of using periscope-like mirrors so that the camera woudl be fully hidden and the view would be through the cupola. This should be doable. Another idea being considered was to mount the camera on a servo-controlled platform inside the caboose so that the camera could be rotated around for a 180 degree (or even larger) view while the train was in motion.
But I still prefer the engineer's view from the cab (as this is what the real engineer would be seeing while driving the train.)