I was just looking at my copy of Alvarez del Toro's "Reptiles of Chiapas" and looked at the black and white pic of the Drymarchon in it. That snake looks very similar to the snake I found in southern Veracruz. He doesn't give locality info for the snake in the photo.
Del Toro lists several color patterns found in Chiapas, including a dark snake with a reddish venter, some are olive brown anteriorly with a dark gray belly, and others that fit the "black tail cribo" description (olive brown anterior and black posterior).
BTW - has anyone else seen the picture of the brick red melanurus in Julian Lee's "Amphibians and Reptiles of the Maya World"? Stunning beast!