You need to ditch the Dial thermometer too. Those are inaccurate as much as 10f or 10-20%. Get a digital accurite from walmart for 12$ and itll read cool side warm side and humidity all in one.

Get the new setup up and going before you switch him over. Then once you have him set up in new SMALLER set up wait 7 days to feed. The more you offer the more hell refuse.

You want to aim for a 90-93 warm side,80-84 cool side and 50-60% humidity at all times.

Heres a idea on how to setup a 6qt tub if you chose that route.