I recently set up my T10's with dividers and RHP's as well.
I just drilled a hole just small enough for the probe to slip through one of the vent slits in the back of the enclosure on the "cool" side. I then ran the wire down behind the shelf (used it to hold the wire in place) and have the sensor about 2" off the substrate. Temps are steady where I set them on the Herpstat and snakes seem content. I see them on both sides and on the shelves as well. Must be working LOL