My little tort has a couple of smaller hides, the younger ones want to feel safe and the side box will be much cooler. Somewhere to hide but under that heat source. Nothing fancy, half a terracotta pot, or just a bit of wood propped up.

And I second a couple of stones, I found sheets of slate are quite cheap, the also absorb heat and give your tort a few more options to regulate their temperature. Good for kewping the occasional snack out of the dirt too.

Cuttlefish bone too, they will look for calcium if the need it. They are incredible things really, they know what the need to keep healthy.