What your saying is true, but, snake species during unsupportive conditions, often stay underground for years, even decades. To me roads,are not a good tool for understanding snakes, roads are a tool for finding them, for sure.
The question is, did they die off, or are they underground.
I can say, I observed neonate hogs at both Santa Cruz co. sites. which means, they are reproductive. Which is a good thing.
I personally know and saw a hog from Pima co. I also heard reports from Pinal county. And in a logical local. But no animals or pics from there.
I would like to see some academic herpers work on Hogs and remove them from colubridae. Best wishes and congrats again