ok im new to having a pet snake. i am going to start from the beginning in hopes that someone will help me out. i bought a snake from a person that mistreated her. shes very malnourished. i took her from this home to make a better home for her. shes a very calm snake, never shown any aggression at all. they fed her once every 6 months and told me themselves that she just will not eat. since i have had her for the last month she has ate 5 times for me with no issue. even taking frozen/thawed from my hand.

so here is my story. i went to the pet store. i bought a 40 gallon breeder glass tank. aspen chips 2 hides red heat lamp a UTH with thermostat a thermeter/hydrometer bowl all the trimmings. i installed everyhting red light over the hide. hide in the cold side with her water. i but my humidity gauge on the glass in the center both ways on the glass. i started having humidity issue so i switched to cypress mulch. every day and threw out my day i wet her substrante to keep it in the mid 50's. she started to develop this flaking of her scales. i with not reallying knowing alot just thought it was from the leftover owners not taking care of her. week later her scales are brownish colored all over her. i take her to a vet a soon as i was able to which was the next day. i was told they was mites. so i went home with my medication and i threw away everything and cleaned everything. not knowing that u can see mites i though they was micro sized. at this time not knowing how i got them i have switched to frozen rats and eco earth coconut fiber bedding. through the course of a few days her scales are getting worse. i went back to cypress mulch cause the coconut fibers were messy and lacey started to develop this desire to dig all day. since i have had her she never dug. now its like the new big thing. so in fear of the fivers getting clogged in her snout i went back to mulch. few days ago this brown stuff was acually scale rot.... ive been keeping all the flooring damp and moist even inside her hide. issue is my meter reads 50-60% and the temp in the mid 80s fearing that im screwing this up the vet told me to get aspen shreddings and clean her tank and get it dry. so i did that. how here is my issues

1 did i place the humidity gauge in the wrong place on the glass? i currently have it leaning on her hide right now.
2 did i mist to much causing this issue
3 now that im using aspen shreddings i cant keep the humidty up anymore. i have a piece of plexiglass on the lid right now
im very scared to mist the tank now even when the gauge says its 40% i dont want to cause her more issues but i know it needs to go back up

right now she still eats like a champ and shes great to take out of the cage she moves all over her cage and house with no care in the world it seems.

and i forgot to mention that i stopped using aspen mulch in the beginning cause she got alot in her mouth and couldnt get it out i had to take it out for her is why i went to other stuff.

could someone please help me with this issue. my house has central air so its cool in the house so its harder to keep the humidity in. if its safe to use a different substance for her flooring let me know such as cypress mulch. i just think ive put to much thought into this layout and screw it all up in the process. and yes i know glass cages are not great. but i currently do not have a way to get other stuff like a pvc cage.