AP snake rack...where to put this probe?

I have a 6 tier CB70 rack setup and one of the plastic strips that cover the heat tape is on the way to finish up the build. I see the slots in the back for a probe so it can lay down on the tape. Do I need to sandwich it between the heat tape and the corrugated plastic cover or do I just set it on top of the plastic cover? I don't want the tub sliding over the tip repeatedly and messing the probe up. I still have some of the hvac tape leftover from when I attached the end of the tape. Also, does it matter which shelf I put it on to get the temperature? It'll be run by the last channel on my Herpstat 6 so it'll be as small a tip as I've seen in the reptile trade.

I usually slip the probe between the heat tape and the side/bottom of the enclosure to help ensure it stays in place. I do put a bit of tape over the cord as well.

Did that interfere with your ability to get the plastic heat tape cover in place?