You could also try having three:
1. A digital one that sticks to the outside with a probe that goes into the hide on the hot side. ($10 canadian)
2. A digital one that sticks to the outside with a probe that goes into the hide on the cool side. ($10 canadian)
3. A digital one that lies on the floor in the middle that reads temp and humidity. This is to gauge ambient temp. ($25 canadian)
The digital ones with the probe are not the indoor/outdoor. It just takes a reading where the probe goes. I stick it on the outside so that I can see it better.
It may be over kill a little but it is precise.
Jimmy