You should have your temp guage place directly on the bottom of the tanks/tub in the hide (due to them spending the most time in it) and get your temps to about 92-95deg on the hot side... 80-82deg on the cold side. Make sure you have it reading right against the bottom of the enclosure (meaning under the substrate) since snakes will push the substrate out of the way usually to get to the bottom of the enclosure...

you should be investing in something like this:

http://spyderrobotics.com/products/herpstat.html

I've been using one with great success... takes the worry out and monitors the temps and adjusts as needed automatically.

Hope that helps,
Colin