You can always provide a "hide" for him, someplace he can go to sleep and/or just feel secure and away from the light. That helps if your beardie feels he's gotten enough UVB for the day plus it can be a comfortable place to sleep.
They are easy to make, if you don't want to buy something, just take anything that you can make a cave out of and place it in the viv where he can crawl in and chill. Preferably something not harmful or fragile that can collapse on him. He might not take to it right away but you can always wait an hour or so after he's gone to sleep and move him in there, sometimes you have to show them all the goodies you provide to make them comfortable. :mrgreen:
The 13G viv is ok temporarily but it never hurts to start thinking about getting a bigger home for him. With proper light, temps, and food, he's going to be super healthy and grow like a weed and that tank will be pretty cramped for him! :wink:
I don't honestly think the 10.0 is going to be too much UVB for the lil guy. If you had a MVB bulb then you'd have to watch out, those provide really high UVB output.