Yeas I am aware that we already have Sherman hill but I am also thinking of the VERY different to the Sherman Hill Like this picture here: I think this would be a great route on the "Golden Age of Steam/The End of the Steam Age and the beginning of the Diesels
Buynot has a thread very similar to this, I suggest checking it out: Sherman Hill 1950s Someone also made a route of Sherman Hill in the 50's that's worth checking out: https://alpenfreight.wordpress.com/portfolio/sherman-hill-vintage/