Saying "I don't understand" was a tactful way of saying what you are trying to do is stupid and backwards.

Please explain WHY you want minimal intervention from the t-stat? If you have a proportional t-stat, it will NOT EVER shut the tape off completely, it will simply adjust the output constantly, dimming and jacking up the heat as necessary.

How do you plan on getting your probe to stay I place overtop f the substrate?