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A few suggestions...

If you don't already have something to control the heat you will need to get either a rheostat or a thermostat to regulate your temperatures. Your UTH is best suited for the bottom of your tank under the hot hide. If it doesn't stick on its own you can get some aluminum tape and tape the edges to stick it on the bottom.

With mesh screen tops and heat bulbs you often have humidity problems. If you are having a problem I would cover part of the mesh with tinfoil, this will help keep the humidity in after misting and such. This along with your moss should do the trick.

Make sure you add another hide so your snake has an identical hide on both sides of the tank so he can thermoregulate as needed and feel secure on either the hot or cool side.

Last... Give him a week or so of little to no handling except water changes, spot cleaning etc. You want to limit the amount of stress on your new little guy and let him get used to his new home.

At only a few weeks old do you know how many meals he has accepted or what he was feeding on before you got him?