Your info about Ghost Ranch is a bit garbled. I can see it from my front window. There is a new book out by Leslie Pohling-Kempes detailing its histroy that is a good read.
The ranch was primarily a retreat for some wealthy families, (mainly owned by the Pack family - founders of 'Nature' magazine), who subsidized the dude ranch. It was never an artist's 'colony' - only O'Keefe had a place there. It is about 50 miles south of Chama, and about 60 from Los Alamos. At the time the lab was working on the bomb, it was only a dirt road, and about a 2-3 hour trip. Quite isolated from just about everything. The ranch was also about 5 miles more isolated that it is today. Current US 84 passes through parts that were once the ranch, and the original entry is now under the Abiquiu Reservoir.
The ranch was inspected and cleared for use by the top scientists for R&R. The 'tea room' at Otowi was another possible destination, but not much else was allowed off 'campus'.
I agree that it is a bit of a stretch to think a the RR would still be around for two years before any decision was made about Los Alamos. Up the line, Embudo was closed as a depot in 1934, so I doubt there was any reason to leave tracks in place to the north, especially with the war effort and the need to reuse all the scrap steel they could find.