1st timer. Please help

[Chronix]

I bought a Mojave ball python. He's still young. I have him in a 10 gallon tank with good substrate. Plenty of stuff to hide and climb in. I am having trouble with his temperatures. I know he's supposed to have a hot zone ranging from 80-95 ( hotter in one specific spot as a basking area ) and a chill zone set at around 75 degrees. I have a 75 watt over tank lamp as well as a medium heating pad under the tank where the light is. He seems to only hang out inside his cave in the dead middle of hot and cold zones. I right now I can't get my tank thermometer to break 80 and I'm worried about him. Brighter light is bad cause the tank is so small.. And the under heater is practically garbage. Please help me out