Undertank heater for green tree frogs?

[slinkee]

I'm trying to get my green tree frog tank set up properly. There is a layer of pea gravel topped with several inches of coconut husk, and live plants. I tried a few lighting/heating arrangements and nothing seems to really get the heat gradient right. I was considering an undertank heater but I don't know if it would penetrate that much substrate or if it would be safe in such a humid environment. For instance, if any cold water should permeate down through the gravel would the glass be hot enough to crack?

[toxxxickitten]

To help heat the enclosure try placing the UTH on the side of the tank instead of the bottom. It wouldn't heat much else besides the bottom of the tank and wouldn't penetrate much with how thickly the substrate is.