So what kind of hides do you have now? Picture perhaps?
The UTH does only heat surface temperature. The lamps are used to increase ambient temperatures. As long as your ambient temps are above 75* and you have a hot spot (surface) temp around 92*, your snake will be fine.
If you can, purchase a gram kitchen scale you can weigh your snake and track its growth. You can also use it to determine how much you need to feed him. I feed 10-15% of the snakes body weight until they are 1500g.