(TL;DR included at bottom)

Hello, I have a 6-year-old female ball python. I keep her in a 40-gallon tank, 36x16x16 inches. The heating pad I have now is a 24watt iPower 8x18 inch heating pad, about the same size recommended for a 50-60 gallon tank. It covers 1/4 of the floor, but it really doesn't work that well; I can only put about an inch of substrate to feel the heat coming through. Using the heating pad and a 75-watt daytime heat bulb, I am able to achieve 88 degrees on the warm side in the hottest spot (the hides do get a few degrees warmer on the inside). By the way, I live in Florida and it's summer, so my house is never colder than 72 degrees even at night.

At night, I turn on a second, smaller heating pad to compensate for when the daylight bulb is off. But it's a lot of electronic accessories, you know? I'd like to be able to use only one heating pad.

Anyway, I decided to spend some money towards making this tank bioactive. So I want to put a good few inches of substrate, make the terrain look layered, go all-out. I don't believe my current heating pad will be able to heat the substrate beyond 1 inch. I would be relying entirely on the 75watt daytime bulb to heat the warm side of the tank, I think. Will bringing the substrate higher and closer to the heat lamp be enough to compensate for this? Even so, I would have to buy a second dome lamp so I can use an infrared bulb to keep the tank warm at night...

So...

TL;DR: What products do you use to heat your 40-gal tank if you have several inches of substrate? I am using both an 8x18 heating pad and a 75watt daytime heat bulb, achieving only 88F in the warmest corner of the tank, with only 1 inch of substrate.

ALSO... My python tends to hang out on the cool end (75F) of the tank anyway, so do I even need to worry about all this?