Yeah. I think it's possible with the right computer software to pinpoint the time based on angles, coordinates, date, etc., but without knowing exactly how GH put it together, I'm not going to rely 100% on it, either. From my interpretation he used Cheyenne's photo and ran comparisons based on the shadows.
For sure I think he and a lot of other people can approximate a time within a limited range, but I just don't know how accurate any of it is. Or exactly how the 2:07 was first determined, for that fact. Frustrating.