I'd suggest read the glass setup sticky thread. (lots of good info)
You can use a tank liner like a repti-carpet and I place my digital thermometer on top of the carpet, this is to limit the possibility of the snake getting down to the glass. (doesn't mean it's impossible. They are the greatest escape artists. Knock on wood)
I've had a constant temp range of between 85-88 with a zillia thermostat. So far the biggest spike I've seen was 90. (Sun, house temp etc could easily affect temps in apartments, town homes etc. Any room that may get exposed to drafts)
I use two digital thermometers, one hot spot, and one cold side. Then I use a el-cheapo analog for air temp, and obviously a hygrometer. I use tinfoil on top to maintain humidity and air temp. Then I use a infrared 50w bulb for added warmth at night.