There is nothing wrong with putting a low wattage bulb over the cage depending on what your setup is like. Many people use low wattage basking lights to supplement their UTH heat which will encourage the snake to come out into the open to bask.
You just want to make sure the air doesn't get so dry as to cause the snake to lose too much moisture. This means a humid hide is a must as well as occasional misting. Even for non-tropical species like this a dry tank will cause incomplete sheds and other issues. Even though when we find these snakes in the wild they are out in the open the majority of the time they are in higher humidity places such as under a rock or log etc.