I believe Sublette was active until the end. Why Sublette? Proximity to the regular rockslides of Toltec Gorge and the moraine cuts between Sublette and Big Horn; easier to get to via road than Osier (speculation on my part - those Forest Service roads were there in the 1960s, but that may not have been a factor). The Antonito section could cover the area to Big Horn with speeders, ditto a crew based (but not living) at Cumbres between Chama and Osier.
I would also suspect that, as the Fifties wore on, men would rather live in civilization (and get to work somehow each day) than be cooped up in a smelly log bunkhouse and a bunch of other smelly guys with no running water, so they said a polite "thanks, but no thanks" to the kind offer of free lodging courtesy the D&RGW.
Just a guess.
JAC