Under the tank heaters...show me your set up please

[Eric Alan]

See we never had a problem with it in the 2.5 years we had it.

Famous last words...

Would the thermostat probe sit between the sticky part of the pad and the tank or do you wrap them in foil tape like I've seen suggested?

Between the sticky part and the tank - don't wrap the probe with foil.

...he's on paper towels and newspaper NOW and I might keep him that way (without a heat pad) or go back to the substrate and heat pad with a regulator.

A thermostat ("regulator") is critical regardless of what substrate you choose. Quite simply, normally functioning heat pads are too hot for ball pythons. BPs are not desert animals are are sensitive to high temperatures. I'm terribly sorry you learned that the hard way and am glad to hear you're working on taking the proper precautions going forward.