I will add.... it would really be good to stop by walmart or a store like that and pick up two Accurite digital thermometers. Get the ones that measure humidity as well. They are about $12 each. Put them both inside the tank, one on each side. That will give you better temps and better readings. I have one like you have here, and it has never matched the three accurites I have. They have always been within a degree or two of each other, so I trust them more than the one like yours.
Aside form that, what the others have said... some dollar store fake vines/leaves would be great. Just make sure there are no "rings" on them that your little guy could get stuck on or in. two hides, some fake leaves/plants and if there is still extra room in there, toss in an empty toiler paper or paper towel roll.
Congratulations on your first reptile. I got my first in November, and I still adore her more and more every time I look at her. They're amazing!