As stated above, try a ceramic heat emitter. Hook it into a thermostat (like a zoomed hygrotherm) and it will turn the CHE on/off as needed which will help with the substrate drying out. You could also spray the substrate directly to moisten it (if you aren't already) but keep an eye on the humidity. With a CHE I end up misting once or twice a day to keep humidity at the right level (usually in the morning and before bed). What temps are you keeping your frog at during the day and night? You said you are waiting on a thermometer and hygrometer but are you checking with another method (IR temp gun, etc)?

Also since these frogs are nocturnal you do not need any sort of lighting. Just make sure your frog is getting the proper amount of vitamins/minerals and 12 hour cycle of light/dark.