A bright light is not necessary for Balls. Most people use it in a tank setup as a heat source, but ambient light in a room is all they need. If you can move around the room without turning on a light, that should be sufficient.

As far as wondering if your snake is thermoregulating... that's actually a common concern with first time owners. I'm sure he uses his warm hide when he needs to (such as during a shed cycle or after eating), however you might want to take the temp in the hide. Quite often people will take the temp on the warm side outside of the hide, but inside the hide can often get much warmer.