The whole project started through a discussion on a thread about recreating 1950s airports - MSFS 1950 - Historical Airports
I knew about the concrete arrows from previous digging about into the history of the airways and a discussion in that thread prompted me to go looking in the sim for three that survive south of Boise.
Sure enough they were there and so when Rob said he was interested in building the beacon sites, plotting the whole of CAM5 seemed the obvious place to begin!
As it happens, Salt Lake City was where Elrey Jeppesen set up his charts company after making notes on the routes he flew for Varney Airways, who had the contract for CAM5.