First and foremost make sure you have a thermostat for your UTH, if not turn it off. I doubt the pre-made habitat kits come with it. Despite what someone in the petstore may tell you, a thermostat is not optional it is a requirement. Well you could use a rheostat I guess and that would be fine just harder to maintain, you can pick up a rheostat (lamp dimmer) at lowes or home depot easily enough. A thermostat might have to be ordered online.

How are you measuring your temps? What kind of thermometer? Where is the probe?

As mentioned above there is no need to feed in a separate enclosure it will only lessen the chances of your snake eating. In general a hiding python is a happy python. If he is out roaming then something is generally not right, they do sometimes come out and explore at night though.

When are you trying to feed him? They are nocturnal so try feeding at night. Also try heating up the prey item with a hair dryer, if he still won't take it then leave it in the cage over night. I'd try a few more things before jumping to live. Especially if he already is known to eat F/T.