Where is the water bowl in your setup? Do you leave the heat lamp on all the time?

In my tank setup, I have been having to turn on a low wattage heatlamp at night since it has been getting cooler outside. To remedy the heatlamp sucking out all of my humidity, what I have done has been to place another water bowl in the setup slightly under the heatlamp. It has been working pretty well so far keeping my humidity up around 55%, the heatlamp causes the water to heat and evaporate, so instead of losing a bunch of humidity to the lamp I am able to keep it steady. Maybe this could help you too??