What kind of thermometers are they? Digital ones with probes?
Ball pythons are such docile snakes that cage aggression is never an issue. As long as you go into the cage on days that are not feeding day, they should never "mistake your hand for food". You don't smell like a rat, you don't look like a rat, so your snake should not just bite you because it thinks it is being fed. I have never heard of a case of impaction with ball pythons. i have had my snakes eat mouth fulls of substrate and be perfectly fine. Remember, these guys digest rodents WHOLE. A little substrate is no big deal.