Here is a scan of my negative envelop for the above image. Development info on it, as well as printing dates (can be tied to printing data that way). Bottom right corner -- suggestions (P for print in platinum, and B for possible negative bleaching -- which I did not do).
Nothing is perfect, of course. I did not record the actual date, but it is the first week of April 2018 for sure -- the month of my artist-in-residence in Zion. I did not write down about guessing on the darkest light values, but might add that now while the memory of taking the image is still strong enough. Also attached is the camera set-up for the Zion image.