One... Your setup seems way more complex than it needs to be.
My ADULT ball pythons are kept in a 34 1/2" x 16 1/2" x 5 5/8" And they have two hides, one on the hot, one on the cold.

Second. About the heat concern, if he likes that hide, move it to the warm side.
Are they all identical? If not, make them all the same size as the one he likes.

A picture of your setup would help, I'm tired and it sounds very over-complicated.