She wont 'get used to it" Im afraid.
Being cold blooded, they need heat to move, and to digest food.
The thing is, you dont want too much heat. This will dry the animal out, and they will start to show signs of heat exhaustion, like holding their mouth open, sunken eyes, super brite colors(trying to reflect as much heat as possible) and dry skin. Its especially important for this species to stay hydrated, well its not any more important than any other species, but they come from a wetter climate, so they dry out easier.
During the day, no matter what temps are, my female jackson keeps her body temp at 83-85F. When trying to digest food (basking) she will raise it to 87F but never over that. Now you dont need to provide a basking area of 87F for the animal to be able to heat itself to that temp. They can change their color, and absorb more, or less heat as needed.
So a basking area in the low 80s is perfect, because it does not dry out the animal, or raise the ambient temp in the rest of the cage up too high, yet it allows the animal to heat up as much as they like.
You want to focus on creating a temperature gradient as well.
Dont have a hot, and a cold side. Have a warm side, that gradually gets cooler, as you move away from the basking area. This means the temperature in the room the animal is housed in, is very important.
If you have an ambient temp of 60F, and a small basking area of 95F, the animal WILL choose the heat, instead of the cold.
If you provide a proper temp/humidity gradient, the animal will virtually care for itself. Your goal is to provide it as many options as possible, as far as heat, humidity(your basking side will naturally be a lower RH), cover, food, and water. The animal will do what its made to do, and get what it needs to keep itself healthy.
Try different watt bulbs, and if one is close to what you want, but a little too high, just raise it up away from the cage further.
Id recommend having your main basking branch, come from the top corner that the basking light is at, to the dead center of the cage.
This will ensure the animal has access to a smooth gradient, as it can just go up, of down the branch.
Keeping her at either 75 or 90 is going to cause health problems eventually.