I used hot glue to hold mine in place about 1.5 inches from the floor in the back of the enclosure worked great for me. Just make sure to keep the hot glue off the probe itself.
You don't have any issues with the hot glue being directly on the heat source?
0.0.1 Normal Ball Python
1.0 Albino Ball Python
0.1 Het Snow BCI
1.0 Lesser Ball Python