Have never seen a 4 or even 5 footer with 13 buttons. Handled one years ago just over 6' that had 12 buttons. My guess is this snake is not 8 1/2' and do agree that the snake is made to look bigger in the pics., but I have no problem at all guessing this snake to be in the 6 1/2 - 7' range.
Would love to see the fangs on this specimen.
Too, a bit off the DB subject but many don't believe the length's nor the aggressiveness of cottonmouth's either...
...until they spend some time around them.
DISCLAIMER: I DO NOT have a degree in Herpetology nor photography BUT have enough experience in both fields to be dangerous....to myself.