Thanks for the tips.
They made it possible to trace the line on TerraServer from Otowi to Santa Fe (in most places). Appears that Buckman Road heading northwest out of Santa Fe basically approximates the RR line all the way to the Rio Grande.
Wow! I had no idea trains had to climb through what appears to be a pretty spectacular pair of loops to climb out of the Rio Grande canyon south of Otowi and head southeast to Santa Fe.
Any known station at this location ("Buckman" on the maps) or photos of these loops?