Ed ~
Sorry to take so long to chime in. Had to get back to my computer where I am logged in ....
Anyway, you are right, WU operated TC wires over the South Park lines from Denver to Buena Vista where they connected with the D&RG lines to continue west to SLC and points beyond.
I am not that well versed in systems and networks, but I do know the South Park line construction and the various hardwares used over the years. I have hiked and dug the ROW heavily and been researching it now for 30 years.
Not sure how I might help you, but if you need history of the construction or hardware, I'd be happy to share anything I might know.
Larry Volmer is an old lineman that worked this area and is quite a resource of hands-on history. I will contact him regarding your WU wire question.
You are correct .... two wires over Boreas. The line from Denver to Como was originally two, then four, then a major rebuild in the teens had it looking like in those two arm photos all the way to Buena Vista, even though the mainline beyond Garos was abandoned at the time. I suspect WU actually did this rebuild to shorten their TC route and just used the South Park ROW in an exchange for services.
The phone line came up via Morrison and Evergreen to hit the Platte, before jumping over Kenosha to Fairplay and on over Mosquito Pass to Leadville. It was totally independent of the RR line, although, by the late 70's when I first stumbled onto it, I think some of the old RR poles were cut over for use in local phone leads down the canon toward Foxton and South Platte. Strontia Springs even shows a Mountain Bell sign on their pavilion around 1910, so the phone was getting in there somehow.