Half log hides aren't the best.. they aren't very secure feeling to the snake. Something dark, tight, and enclosed on all but one side is best. Lots of people use those houseplant pot bases.. you know the plastic circle you put under the pot to catch water. Just cut a hole in the side or top, and voila.. a nice hide!

Also what are you using to measure temperatures? Those little dials or stick on strips are terrible. If you don't have one, get a digital thermometer/hygrometer from target or walmart. You can get the indoor/outdoor ones made for household use. They're much more accurate for measuring temps and humidity.

Under tank heaters without a rheostat (like a lamp dimmer) or a thermostat on them can get dangerously hot. You can either use just the lamp (beware this removes a lot of humidity though) or get a rheo/thermostat for your under tank heater. They are dangerous to your snake without one.