setting up a heat lamp with a thermostat

after getting my new baby im planning out her future viv and could use some help.im going to have a 100w red bulb on a dimming thermostat but wondering where i should place the sensor and what temp i should set the thermostat to so i get the 90 hot spot and ambient temps up.may sound stupid but im not sure if it should go in the hide or outside.its going to be a 3 foot wooden viv.

I would recommend ditching the heat lamp and just hooking a under tank heater (UTH) or some kind of radiant heat panel. All lamps tend to do is dry out the enclosure.

The thing you want to remember is BP's don't care about the ambient temperature of this enclosure. Ball Pythons only care about the surface temperature on the floor of their enclosure. Which should be 78-83 on the cool side and 88-92 on the warm side.

I'd recommend placing the probe on the surface of the warm side, over the heating element. I'd also recommend a IR thermometer for measure the surface temps of the enclosure. Something like this:www.tempgun.com/