I filled out the survey, good luck.
I feel you should ask what kind of tortoise as the care for them varies so much as well as size.
Maybe also include if this would be a temporary/starter enclosure or their permanent adult enclosure.
I hope this little bit helps.
You say you still don't understand why this is happening now and not earlier if it's the environment he's been kept in. - Nothing happens fast with a tortoise, they can be kept in bad conditions for decades and then finally the symptoms that maybe were there all...
I don't think I've seen anyone suggest a heat mat to help temps without drying out so much. This may also help get the heat directly to his organs where he needs.
Good luck, and it's so sweet how hard you're trying for your tortoise.
What kind of horse hay pellets are you feeding and to which torts?
I was just looking at Tractor Supply that has Timothy or Orchard grass pellets in huge 40+ lb bags for under $30. I was thinking the normal Mazuri 5M21 has too much protein for Sulcatas and a ton of extra stuff while these horse...