yes, thermostat probe stays on the outside, sandwiched between the tub and heatmat. it's the thermometer probe that stays on the inside:
~~~~~~~~~~ <-- substrate
---------o------- <-- thermometer probe
========== <-- enclosure bottom
---------o-------- <-- thermostat probe
------------------ <-- heatpad or heattape
or checkout this supercool/supercute/superhelpful diagram: https://ball-pythons.net/gallery//sh...mageuser=19365
also here's a quick guide on tub setup: https://ball-pythons.net/forums/show...e-Basics-*DUW*
stuff like pee or spilled water than throw off the thermostat's probe reading of the temp u set it at.
Edit: clips or luggage straps can help u secure the tubs.
Edit2: a second hide is not necessary but pay attention to your BP, but most of those BP's are in racks where it's dark. if it seems stressed and out of it's warm hide, move to a smaller water bowl and put in a cool side hide. Or move the tubs to a rack, shelf or something that covers it's sides.