i have mine propped against the corner in the cool side and the probe inside of the warm hide. that seems to be accurate enough for me.

and i would recommend getting a thermostat (no rheostat-they work differently, and in my opinion not as well). that should take care of your temperature issues altogether. if it is still too cold on the cool side after hooking a thermostat up to your heating pad them you could add a heat lamp or something, but it might not be neccesary. or you could put another thermostat regulated heat pad under the cool side to avoid lamps and their negative affect on humidity.