This is going back a long ways, but some years ago "Lee Helm", a frequent character in the "Max Ebb" section of Latitude 38 published a neat little program for determining the sun's azimuth. Written in Basic and only a few dozen lines of code... input Lat/Lon and time, output current
azimuth. I had it programmed into my old Toshiba pre-laptop, but code and computer are long gone. Her application was for compass
correction, but it might well do for your situation.
Now, how to get a copy? Beats me! Lat does have archives
, but possibly not going back that far... this was in the late 70's or early 80's, while I was still a worker bee. Some internet research
might well dig it, or an equivalent code out of cyberspace.
Good luck... and I too wonder about your Bagnold sun compass technique.