I'd recommend most definitely getting a UTH, number one. Number two, I'd ditch the fogger and use this instead: http://ball-pythons.net/forums/showt...tank+treatment
I used this tutorial and it immensely helped with controlling humidity! What kind of substrate are you using? I recommend using coconut fiber substrate, since it holds humidity well. I use both of these in my BPs 29 gallon tank, along with a UTH on a thermostat and a heat lamp on a timer. His ambient temps stay around 82, hot side around 90, and cool side around 80. Depending on how humid it is here, his humidity stays around 40-60 with the tank screen treatment and coconut substrate. Hope this helps!