Rattlesnake, Baja California, Mexico

I heard this rattlesnake long before I saw it, and I can tell you I backed up so fast I almost fell down the hill we'd just climbed up. It was so well camouflaged that even after I stopped to look for it it took me a good few seconds before I could see it.

I have tried IDing this rattlesnake but even individuals of the same species can look widely different. I'd love some help if anyone knows. It was spotted on a trail in Baja California Sur, Mexico.