In addition to the issue of 30" gauge coupler height, the prototype 3 foot gauge rilroads also used different heights and size xcouplers in real life. Some of this prevented equipment from being sold off to other railroads easily. Teh Colorado Rilroads used the height and couplers used by the DRG&W first as they had to interchange with them.
Some smaller prototypes used a lower mounting point to direct thrust to keep the cars stable. The idea of one coupler height for narrow gauge is not a real world scenario.
Some smaller prototypes used a lower mounting point to direct thrust to keep the cars stable. The idea of one coupler height for narrow gauge is not a real world scenario.