Well........ First 75 gal, is way WAY to big for a ball python. Especially if it is a baby. They need to be at 50% humidity, or you are going to have trouble with sheds, and eyes cracking. They don't like a lot of space. She'll probably be nervous all the time and not eat for you.

Second. I'm sorry, but if you can't afford a heat lamp, you shouldn't have the snake. they are expensive creatures. Heat lamps will possibly dry out the enclosure, and they are better off with belly heat. That comes from an Under Tank Heater (UTH) and that is more costly than a lamp. It should also be hooked up to a thermostat, or you could burn your snake. They need a hot side and a cool side to thermoregulate. One at 90-92 degrees and the other at 80-82 degrees.

You also need hides for her to sleep in. Cereal bowls and such. And, a thermo/hygrometer to measure the temps and humidity on both sides.

Go ahead and hook up that light to give her some warmth. and mist down her enclosure to keep the humidity up. But not too much. You don't want a respiratory infection on your hands.