Steam loco operation

[Sumpter250]

The simplest solution is to model whatever you want to and then add an excursion steam line. That way, it can be any era of steam loco you like.

Or........Have the owner of a large local industry, with a narrow gauge industrial, steam powered rail line, buy up shortlines, and operate them with rebuilt steam locos, as a subcontractor to the local class 1 roads, hauling less than carload loads in steam era equipment. Then, build and operate railfan "photo op" sites along the short line right of way, to provide a place to take great, "otherwise impossible" photos of steam era freights, for a small fee.
It helps, when the "large local industry" is an established ship yard, with all the steel working, boiler repair/building, and carpentry shops, necessary to maintain the railroads. It also helps that the owner is an avid steam fan.
OK, it's weak, but that's my story, and I'm sticking to it.