Have you tested those hygrometers anywhere else but the enclosure? Do they actually function?

You can go get a digital hygrometer/thermometer combo unit from WalMart for $15, and it will help you determine whether or not the dial-gauges are even functioning properly.

The humidity in our house is normally 50-60%(Can you say "Bleh"?), and my Rosy's tank is just like yours, heat pad and screen lid, but no light. He seems to be doing fine as I have a tiny ceramic waterbowl(think rodent food bowl-2" in diameter) in the tank for him and it hasn't raised the humidity any.

Hmm. You can always try smaller waterbowls, turning the air conditioner on more frequently to suck some of the humidity out, or you can put some heat lamps in the room(I don't know, if it works in the cage, why wouldn't it work in the room). Try a few things and see how it goes.