I think John's idea is worth serious consideration. With enough engines active and trains running, there are going to be some good pictures available over several days, just by being there and being creative.
The idea of railroading at night, not just static flash shots is a great one. My best memories of steam are at night, when the camera's were in the bag and I was just watching. Trailing steam, lit from below as the fireman heaves in more coal, the flicker of the markers and switch lamps, the circling back up signal of a brakeman on the ground, the hum of the dynamo, whistles echoing in the dark, it's a sensory extravaganza. Figure out how to do it and I'll be there!
Sounds almost like Plandampf!