If you can't peel off a UTH heater OR your probe is to big to sandwich between UTH and tank, you can put it UNDER the UTH as long as you put something UNDER the probe (length of entire enclosure) to keep the probe in place and touching the UTH, secured and safe. Like something along the lines of styro foam, with a small indentation for the probe to sit in.
You say this is the "first" time you've put the probe like this, and its simply not as dangerous. So...you admit you've not done this for long, yet your short observation trumps years and tons of experts advice ? Some of it based on mistakes that animals had to pay for.
You keep saying "under the right circumstance" its totally safe.
So, for arguments sake, exactly what are those circumstances. 1. in a glass tank 2. PVC or plastic cage 3. Tub ! Using no glue, tape nor screws, like you already said you didn't. Also...keeping the cable that goes to the probe safe and keeping the snake safe from entanglement.
Just exactly what do you do that is SO great and SO easy and SO sure that its better then to simply put the probe where it belongs. Right on top (or bottom if secured right) of the UTH. And is your animals safety worth that ?