I have a 20L with a 75 watt bulb. The hot side is at 87 and the cool side runs around 80. I have a UTH with a thermostat between it and the glass. The thermostat is set at 98 and the floor temps run around 89 even with the light shining on the substrate. I have a piece of 20 gauge sheet metal over the screen with a section cut out right where the heat lamp sits. The humidity is usually between 55-60. I can raise the humidity during shedding to 65-70 by misting daily or wetting the moss a little.
This is what I have found that works for me. Everyone's combinations will vary depending on where you live and the indoor temps you keep. I bought 50 watt bulbs to find out I had to go back and get 75 watt. You may have to do the same to yours. Like I said everyone's will be a little different.