I keep my brb's right in the low 80's. Highest it goes is 85, so generally it's hanging out around 82-83. I use cypress mulch, it keeps the humidity right around 65-70%. I do not let it drop at night.

Ceramic heaters will suck up the humidity. I'd ditch it.

I keep both of mine in a tub, with an inch or more of cypress mulch that they can burrow down in. We use an on/off thermostat (Ranco) and have it set for 85 F with the 3" flexwatt running along bottom back part of the enclosure for a gradient.

Pictures of your set up will help us...