Another option would be instead of light bulbs, a ceramic heat emitter (CHE) for the cool side. You can still plug this into a dimmer and then into the thermostat that controls the hot side. In this case, you don't need two thermostats. You don't need a night-time drop.
For measuring temps, I highly recommend an accurite weatherstation. This unit will measure, humidity, hot side temp (with a probe) and the ambient cool side temp. You can find these at wal-mart, lowes, or the home depot. You might have to do some digging to find one.
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