If you put screens in the roof of the cage, doesn't that just let all the humidity out? I guess if you set the light right on it maybe that would be ok. Those things get damn hot though, I'd be worried about the metal screen getting too hot and burning my snake. Is that just paranoia? I currently keep my lights suspended a few inches off the metal screen on my tank.
Maybe I'm just confused on how well a RHP will heat the cage. I was under the impression that it would create a good hot spot, but do nothing to keep air temps up throughout the cage. Then again I see people put these in the middle of the cage, would think it should be on one side if that was the case. Animal plastics has the T8 on sale now for $150, maybe I'll have to look into it. Now I just gotta find something to put in this ExoTerra tank, can't just have an empty tank sitting around.