I'd just like to second what Keith has written, especially when he writes "A quick study of historic photos in the Dorman books indicates a proliferation of standard industrial fixtures: radial waves and spun lids with a bit of a shield to keep the light down."
Perhaps a useful reference would be the lighting used at the engine facilities at Alamosa (pole mounted as well as building mounted). Just today JBWX posted a photo of the Transfer Table that includes a pole-mounted fixture of the kind I think Keith is describing. The logic is that the engine servicing functions at Chama in the C&TS era have evolved into the same functions previously performed at Alamosa.
The only exception I'd take to Keith's comments is that I think the previous understanding among SHPO, the Commission, and the Friends is that Chama ought to represent the SJ Extention in the 1940's-1950's. At least that's been the requirement regarding the shingle selection for any rehabilitation of the Chama Depot.