Beautiful enclosure, but I agree with Ashleyraeanne with regards to removing the eco earth. Instead I suggest paper towel, slate tile, or tan-colored reptile carpet-type products. Eco Earth & other similar substrates will definitely NOT get digested if swallowed (by a leopard gecko specifically). If it matters at all, I’m 100% certain of that, and i’m a vet. Leos sometimes will ingest bits of their substrate (instinctively, not consciously) if their nutritional balance is a little off, thus how the dish of calcium powder works. So, given that you are a beginner, it’s safest to use a non-particulate substrate.
I might be misreading your description- did you mean to say that it’s only in the 70s on the ground? Leopard geckos are terrestrial, and though they can and do climb a bit, they should never have to do it. You need belly heat (radiating heat from under the tank), and the hot end absolutely must be at least 85 on the ground. In a lovely 40 gallon tank like you have, honestly, I’d lift the hot end to around 91.
My probe & temp gun temps sometimes correspond to thermostat temps, thermostats can, at times, be inaccurate. For example, I set up a new 10 gallon tank recently and wasn’t paying attention when I put everything together. But then I found that the temps didn’t match. Turned out I had set something over the probe which trapped heat, and was causing the thermostat to read much higher temps than the actual surface heat, where the gecko was - so be careful with thermostat probe placement, it can really muck things up!
The cold end is too cold, in my opinion. For a beginner keeper, I’d avoid any areas in a leopard gecko tank that are below like 76 or so, even at night and with an enclosure.
I wouldn’t harp on it, but I feel the temps you described, unless I am mistaken, will probably kill him. They’re at least part of the reason he’s not eating and he’s sleeping a lot. Way before even starting in the veterinary field, I had a gecko named Stewie, she was the first hatchling I ever hatched. I wasn’t paying close enough attention to her temps, and her tank heater died. She was likely in temps comparable to what you describe, and she died. I’m hoping what I learned with a terrible loss might help you and your little dude out.
Oh, I see about the food-throwing ;). I’ve never managed to get any of my guys on any sort of schedule, so let us know if you learn any good tips! I have a male named Rasputin and he is such a pain about that! As an aside, since he is a pet you will have for his entire life, I’d suggest considering adding some feeder insects into his diet that have less chitin and have better calcium balances.
Side note: he is sooo freakin’ cute! I love the pic of him coming through the hole towards the camera!