You can't vary temps across the same piece of flexwatt. You would need two pieces of flexwatt and two thermostats to set each piece at different temps (or one thermostat that allows two setting).

With one t-stat and one piece of flexwatt, you set up heat on one side of the enclosure with the Flexwatt to get a hot spot at 92 deg......the cool side temp or ambient temp depends on the enclosure setup. If heat stays in the enclosure well, then there should be no issues getting the 92 deg flexwatt to give you an 82 ambient temp. If the enclosure is too cold, you may need supplemental heating.