Making multable engines does make sense. Let me take this idea further. If someone (with lots of capital) would go into business manufacturing steam locomotives for the tourist railroad trade, they would probably find many ready customers.
Say they designed and built a basic 2-8-0 based on the standard Baldwin design. Each railroad could decorate the locos to match which ever appearance they wished (I.E. the addition of a bear trap and air tank between the domes, you'd have a good facimily of a C&S loco).
With many locos built under the same basic design, and a large parts inventory, this could be a profitable business.
Just some rambling thoughts.