You can push the probe through the bottom of the pocket if you don't know what you are doing and get the probe to the tip of the tail so it is really hard to answer the first part of the question with any real certainty.
Exactly how many scales deep are we talking here?
Have you tried popping the snake instead?
And no you can't tell anything reliably from the spurs length.
dr del
Derek
7 adult Royals (2.5), 1.0 COS Pastel, 1.0 Enchi, 1.1 Lesser platty Royal python, 1.1 Black pastel Royal python, 0.1 Blue eyed leucistic ( Super lesser), 0.1 Piebald Royal python, 1.0 Sinaloan milk snake 1.0 crested gecko and 1 bad case of ETS. no wife, no surprise.