Salute!
Good point oggers.
OTOH, the question seemed to only require a measurement of the sun elevation from horizon or true vertical, but not corrected for the "azimuth" you described.
To get the best solution, I would use the time from pt 1 to pt 2 that the sun or star or .... reached the same "elevation" . So in that case the delta could be related to the one minute of longitude for each "clock" minute, corrected for the cosine.
Keep going oggers, somehow I feel we need to have at least an intro to celestial nav principles for some folks visiting here.
Gums sends...