Precisely.
OP: I know you have your snakes best interests in mind but you are putting YOUR needs before the snakes whether you think so or not. I know you want what is best for your snake.
You -think- he needs more space. He doesn't NEED more space. Would he be okay with more space? Maybe. There are a lot of issues with having a big tank:
1. Security issues. Ball pythons are shy snakes and actually get more stressed by large enclosures.
2. Temp Gradients and Humidity are harder to maintain in a big tank. Usually, people get big tanks which are unnecessarily tall. Ball pythons are terrestrial and are not known for climbing at all. Having that extra height just means that you have to heat, cool, and maintain proper humidity for no reason. The snake will never be there.
3. Cleaning. The bigger your tank, the more stuff you have to have in it and the more stuff you have to clean every month. Cleaning a tub takes me about 5 minutes. Cleaning a normal sized tank takes about 30-40 minutes. Imagine cleaning a monster tank and everything inside it. It is no picnic.
If you don't think you can maintain temps, humidity, and a safe and clean environment, then don't get a larger tank. A 30g is more than enough for even a big female.
As long as you can fit two identical hides and a water bowl, the snake will be perfectly happy (assuming temps are correct).