Whats the temps on hot/cold sides? That's one of the biggest things when it comes to leopard gecko housing.
It's a nice looking setup, I'd be careful with the skull, is it easy to get him out if he craws in? A lot of the fish things are nice, but geckos can get stuck in them.
I have the left side in the high 70's low 80's and keep the shed hide on the right, in the skull. Yea he can get out of the skull because it has no bottom. And he can fit out the sides.
Nice gecko and setup. You might want to consider changing over to ceramic tiles in the future because that reptile carpet is a pain to clean, gets smelly quickly and can house lots of nasty bacteria.