UTH falls off :/

I vote foil tape. As already stated that stuff STICKS, plus it has no problem holding up to heat.

Make sure you clean the area before you tape it too, otherwise its going to cling to any dirt or dust particles and then fall off. But, if you are using a thermostat the probe will for sure cause a bulge as stated above. But i know what you mean, i used to worry about the smallest things for about a year after i started.