I would rather prefer to have a free camera before the train like trainspotters and not behind. Add an option to decide if it is behind or before the rolling stock when it runs would be nice. It's quite annoying to follow with a free camera a TGV at 300 km/h speed.
Did you ever press 8? That’s the free cam by default. If you play on console check the settings page for the key for the free cam.