Greg,
Thanks for all that extra work to show a schedule and capacity plans. I think you have a very good plan with the early morning Chama-Cumbres turn. It is the same pattern that was used on freights.
Is it possible the Antonito to Chama bus in the morning could stop at Cumbres and pick up the railfans that might want to make both trip up the 4% all in one day of covering the whole line?
Someday, maybe rebuild the Snow Shed and use it as a car storage building and service barn. It could have doors back (out of sight)in the entrance for security.