I have two heat lamps set on top of my cage that are on a different thermostat than the UTH, to keep the ambient temp correct in the cage. My roommate keeps the place at 72 at all times, so I use them to keep them from freezing. It also happens to work out that the lamps don't come on very often, so I hooked my fogger up to the same thermostat and it keeps the humidity at about 65%.
Only time I use heat lamps is when the heat pad is not enough to keep the ambient temps up. For instance, in winter when it gets freezing! Ground may be warm and up to temp, but nothing else is! Including the top of the snake! Then we bring in the ambient temps, and bump up humidity to make up for what is lost through heat lamps
I have to use a heat lamp to keep up my ambient temps, because a uth just doesn't cut it for an enclosure taller than 6". Just get a piece of plexi cut to fit the majority of your screen. I never notice much of an increase with the lamp over the bowl--if you keep the screen-top open then your humidity will always be low.