This is an interesting question.  Although I have never located any literature which dealt with this type of site, I can offer some information which may be helpful to your research.
     First, what railroad is this deposit located along?  I am assuming it is the Alaska Railroad, but the depositional processes which leave these remains could vary dramatically depending on if it was a standard gauge common carrier or a narrow gauge industrial railroad.
     Second, is this deposit along a single track mainline, or is there (or was there) a passing siding at this point?  If a passing siding was present, this could reflect use of that siding by work trains or US military trains.  These could house large numbers of people for extended periods if work needed to be done, thus leaving a large assemblage such as the one you mention.
     Third, is the debris scatter located on one side or both sides of the track?  This plays into your hypothesis about caboose or Diner waste.  If the debris is located only on one side it would make this interpretation slightly less strong, but some dining cars located kitchens toward one side, with a small aisle being located to the other for access through the train.  If your railroad used this car layout, it would support your interpretation.  Also important to this question is whether passenger trains were turned at each end of their run, or the motive power was shifted for a reverse trip.
     I would also be interested if any literature is availible for this type of site as railroads are also an interest of mine.  Good luck and I hope this can be of use!

Regards,

Stathi Pappas
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Efstathios I. Pappas
Doctoral Student
Department of Anthropology/096
University of Nevada, Reno
Reno, NV 89557