Since steam is a heavily request for TSW, I think it would be good to add either 4014 or 844 as DLC for the route. It could be used as a “test” to see how steam trains work in TSW. Of course, it would come with UP passenger cars and the water tenders.
Yes, steam is heavily requested, and yes these locos are too, but the first steam locos will probably be tanks for WSR or something similar- the locos in your suggestion are extremely complicated and would be difficult for a first loco.
I didn’t even think of that. It’s best to start small, what I like to say. Maybe something along the lines of a GWR 5700?
I've always thought a Pannier tank or something of that size or possibly even smaller would be the first steam engine DLC to come to the game. Though it would be nice to one day have big articulateds and high stepping passenger engines in the game, though certainly AFTER experience with steam and its nuances has been gained.