My controller turns heat on at 92 and off at 93. I keep a pan of water inside and humidity runs whatever, I cant control.
I use a 48 watt proportional digital heater from the Incubator Warehouse. http://incubatorwarehouse.com/48-watt-incukit-dc.html It holds a temp within 0.1 dregrees of your desired set point. You can control fan speed also. As the temperature in the incubator drops the heaters start to power up a little at a time. Say 10%. If the temp continues to drop the heaters gradually increase until they at 100% output. As the temp increases and approaches your set point the heaters drop output until it hits the set point.This is a complete unit. Heater, fan, thermostat and remote sensing wire. The unit only cost $49.99. It comes with the AC converter, but not the adapter to plug into a power outlet in your truck. I rigged up a DC power adapter for about $5.Wisnewbee, could you please provide more info on your heater,thank you