Jonathan asked to see the clearances between the backboards and the line to the fiddle yard. Here you are: The 4 wheel coach is about 54 mm long and 24 mm wide (approximately 2.1 x 1 inches). The clearance between the coach and the backboard is around 7 mm (approx. 9/32 inch). The distance between the coach and the mounting block holding the screw is even less, around 3 mm (approx. 1/8 inch).
I hope none of the passengers lean out!