Do you have a thermostat of any kind?
Chlorhexidine is one of many chemical disinfectants. It is easy to use and relatively not toxic (it kills germs and bacteria and viruses no it is somewhat toxic to kill things.) and is unlikely to harm you or reptiles in general. A local vet may carry the 2% or 4% Chlorhexidine. The 4∞ is surgical scrub and 2 is a general use many would recommend a dilution of 1:24 for the 2% and 1:48 for the 4% it is a spray on wait and use product (I rinse out water bowls but cage stuff I just spray it on wait 20 min and whip out any extra)
However bleach also works well but it IS toxic to your snake so careful rinsing is required. Vinegar is also a decent disinfectant as well household pickling wiped on straight and left for 20 min kills a wide variety of nastys as well, rinse it off carefully but it isn't quite as unpleasant as bleach.
There is also new studies being done on bleach vinegar mixes but I have only read them in passing so you would have to look it up yourself acidified bleach.
A proportional thermostat eliminates the concern about burrowing, the heated surface stays at the temp you have set. (helix/herpstat). It is hard to tell from the photos but it could be a burn, better images would help try having the snake smaller in the frame and crop in on it after just a suggestion.