So I'm considering using flexwatt heat tape to raise the ambient temperatures in a rack as opposed to using a space heater.

Would I be able to use 12" flexwatt (23 watts/ft) with 4" flexwatt (6 watts/ft), and have the thermostat probe on the 4" flexwatt maintaining 95F (or whatever I need for a hotspot), and simply use a dimmer switch off the thermostat output to control the temperature of the 12" flexwatt? (12" will maintain ambient temperatures) Both would be connected to the same thermostat, regulated by the temperature on the 4".