Wildlife Spotting

Yes, interesting observations.

Length and dark-light repeating squares dorsal pattern looks like Pituophis catenifer group to me. However considering range, then your spotting locale puts it in the range of the western subspecies (according to http://nmherpsociety.org/reptiles/snakes/pituophiscateniferaffinis/index.html ), Pituophis catenifer affinis, known as the Sonoran gopher snake. I suppose they also mimic rattlesnake behaviors (?) but perhaps there is individual/situational variability...Maybe wait and see if other users concur or chime in if you have reservations. :-)