Drill a small hole in the side of the enclosure, near the top and close to the RHP. Insert probe and enough cord through the hole so the probe hangs about halfway down the wall; when it hangs like that the snake really can't interfere with it. Adjust thermostat up or down as needed to get the desired hot spot temperature under the RHP as measured with an IR thermometer or temperature gun. I usually hold the probe cord in place with a piece of tape on the outside of the enclosure.