I agree that your setup looks very nice and you're in a good place with your new scaly family member! Unless he is moving around in a very repetitive, stressful way I wouldn't worry about him poking around the enclosure. I've never liked the old phrase, 'a hiding ball python is a happy ball python' because snakes are naturally curious and interested in their surroundings. While ball pythons are definitely on the shy end of the behavior spectrum, you still want to see them relaxing in various areas of the enclosure and not just sitting in their hide all of the time.

Every snake is different, and some BP are fairly active even during the day. If yours is, just be sure he's calm and curious rather than stressed and trying to escape.

Also, don't worry if he doesn't spend much time in his warm hide. Every single one of the snakes I've kept has typically used their warm hide only when they are getting ready to shed or sometimes right after eating. Aside from those very specific instances, they seem to prefer the cooler areas of their enclosures the rest of the time.

If you want to make the larger hide more snug for your little guy, you can also just stuff the inside of the hide with paper towels. That will allow him to crawl around/under the paper towels if he wants to.