Agreed, you really need to have something to measure and make the humidity correct or your going to end up with alot of bad sheds and alot of other problems associated with improper humidity. Heatlamps also suck the humidity out of tanks too. Id look into buying a heat lamp

Get some screen top locks if you haven't already, or he will escape. Do not get a bigger tank, hes just exploring. Height really is not important with ball pythons. They like small enclosures. ( But not too small...) Snakes also see in Infrared, so him seeing out of his tank is not important, it will more than likely stress him out than help!

Hope this helps,
Matt

Posting pictures of your Tank would really help!