I thought you said you didn't want light on. Plus the ceramic is a more efficient heat source.
I understand the UTH is on the outside and you have substrate on the inside. Ball pythons will burrow closer to the heat source over time. You may think it will just go to the cool side to cool off but it will not. These animals are stupid and will burn themselves. It is always recommended that the temp UNDER the substrate be around 90°. Yes your substrate on top will be cooler but your snake can find it's way down to the warmer spot. His spot on top of the substrate should not feel warm to you - your hand is 98° so if it feels warm there's a chance it's too hot for him. Making sure it's not too hot is more important than humidity in the short term.
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