Hmmmm...I dunno about a thermo controlling two totally different heating devices. I suppose as long as you have the lamp on a rheostat it could be okay, provided you throttle it lower than the heat tape.

I would suggest taping the probe to the heat tape, outside of the enclosure. If you have to have that lamp on the thermo too, make sure it's throttled a lot lot cooler than the heat tape. Otherwise, I would put the heat tape on the thermo and the lamp on a dimmer.

JonV