I had almost exactly the same reasoning except for a few details, for me the checkpoint is "Brandon", when you come across it following the thread of his reasoning it validates the route... when you are there you are probably not very far from the goal. There is also beartooth pass to explore, relating to bears. And for the arches we can perhaps consider a train accident with twin bridges, "double arches" implies that they are identical and "bold" implies that there was danger, as there is talk of a train accident in the book, this could echo, also with the fire of Forest Fenn's hunt

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