I can't stress enough that I would turn his fluorescent lamp off. I have personally had UVB bulbs damage an amelanistic snake's eyes.
They hide a lot, so don't get much exposure, but those bulbs don't put off appreciable heat anyway, so at best it is doing nothing -at worst, injuring your reptile. I would look into an under the tank heater, too. Flukers makes one now that maintains a constant 100 degrees. I won't say you *should* run it without a thermostat, but it would probably be safe to in that large of an enclosure. Finally, I would consider a thinner layer of substrate besides carefresh. Hard to find poops and so forth in inches of substrate, you'll tend to keep a shallow layer more tidy. And handle him once in a while! They're great animals because they don't need attention besides their basic needs, but nothing wrong with giving one a chance to stretch out and explore some fresh air once in a while. They're inquisitive, cool creatures. Welcome to the forums!