In my T8s I have the probe fed through the routered channel for the RHP power cord (I had AP install my panels). I have it hanging about 1/3-1/2 down from the ceiling and set to ~87°.
I use a similar method with the t-stat probes for all of my RHP's. By letting it hang between the RHP and the enclosure floor the snake doesn't mess with it, move it, pee or dump water on it, lay on it, etc.