I think your on the right track. There is a lot of open space, but that can be fixed easily.

It's best to give your snake an option of two identical hides on each temperature gradient. Meaning, have a hide for the hot spot, and a hide for the cool end so he can choose to thermoregulate without having to choose security over warmth.

It's also a very good investment to buy an Accurite thermometer/hygrometer. The probe should go on the hot spot, and the unit should be placed on the cool end to measure the air temps and the humidity.

Other than that, putting crumpled newspaper in for him will help him feel secure and move between both ends. Ball pythons like to feel something touching them on all sides, their number one priority is security. Even more when they are young.