http://www.reptiles.swelluk.com/rept...tor-26225.html

Interior mounting such as you are speaking of (with the UTH inside the enclosure) a waterproof UTH should be used one designed for this type of use. They are very costly products (http://www.kanemfg.com/) Even then there are other issues that would need to be addressed before attempting such a thing (fail safe, probe securing ect.) If the probe moves with a conventional system it is quite likely to seriously injure or kill the animal. This is not a practice that should be taken lightly or even recommended.

The solution to the UTH IMO is a different bottom wood makes a grand insulator but a very poor conductor so using a different material bottom is far safer and easier PVC (not expanded) makes a very good conductor and ridged bottom material and is far preferable to the installation you are proposing.

typically RHP and UTH do not heat air anyway (radiant heat sources) this is not part of the ambient air temp equations. Heat sources that effect humidity are heating air ones that do not are not. Some have used heat syncs to transfer heat from a RHP to air effectively I personally do not have experience in that. Although if a RHP is making great increases in air temps then I feel it represents a safety issue and at the very least a fail safe would be needed. Some here have recommended caging then in low height installations as well although if that is the case the over all height is infringed on.