Ah, I thought you meant they had shown some sort of groove being made for the clips, so that wouldn't happen? Rats!
FYI, I use this same type of UTH (Flexwatt) with clear clips over the connections, but I'm using glass tanks for my colubrids -not PVC enclosures that stack.
What I do is apply weatherstripping* (it's peel & stick) to the bottom edges of all tanks, then leave a few gaps in the weatherstripping* for wires to emerge without the tank sitting on them, & also to allow the recommended "air gap" for safe heating (to prevent over-heating). Maybe you can do the same thing? That way the whole UTH will be under each AP- as deep as desired. Another benefit is that the cages or tanks don't slide easily- they've got "brakes".
https://www.homedepot.com/p/Frost-Ki...734H/100047977