You can also use 3 seperate cardboard boxes in the 75 gal tank and turn each into a seperate environment. The most important is temps and humidity for each. I refer you to a ball python care sheet for these correct #s...also, I have seen some use dog or cat water bowls, plastic, as hides cutting a small hole in the side for entry and exit. The hole should be no smaller than the girth of the snake at its fattest point.
Your female could be most likely looking for a mate rather than companion. This could attribute to her behavior. Paper towel can be an adequate substrate but if they soil the box, replace asap to ensure sanitation. I once kept a cpl hatchlings in empty clean plastic coffee containers until I had their setups correct. Not ideal but worked perfectly. People tend to be brash on forums for several reasons but most are just passionate about snake keeping. Try not to take offense to the small minds of others. Temps and humidity are the most important providing adequate hides, placement of temp probes, etc are all examples of "correct husbandry"...
Most people tend to forget that these snakes are not native and they have no clue of their original environments, droughts, rainy seasons, etc...nature is definitely not a robot but the care sheets are developed by those with great experience and knowledge of "snake-keeping"