Welcome! Sounds like he's doing good, but yes, I would think that you want the hide towards the warm spot until you can get another hide. Even an old yogurt cup or tupperware bowl will work for now. Just so he has the choice, and doesnt get too cold because he feels more comfortable on that side. They will take security over warmth most of the time.

You can crumple up newspaper to fill the tank to make him feel a little more secure, and that can make him more apt to thermoregulate.

Hope that helps!