Its not mounted to the panel, its mounted to the rim. The tstat probe does not and should not touch the panel. It may look as if it does in the pic but it does not.
I do not like mounting it down the wall as it can be pushed and or covered by or with the things in my cage. Where I have it mounted it can not be moved or covered by anything.
If you are using a temp gun to set the temp no matter what temp you want the ground or a perch my mounting method will work just fine.