If you have a room temp that is cool and variable you may consider mounting the probe to the glass over the place where the uth is. This will provide more stability in temps. You will need to very firmly fix it. I use hot melt glue place the probe down dry and run glue along the sides and over the top I also run along the cord back most of the way inside the enclosure. Make sure it cannot be moved you should be able to push and pull at it and not move it. Then run your substrate over it set the t-stat to a max of 94 and you are done. Don't place too much substrate over the hot side it is a great insulator.

If you choose to go this route I would also recommend a failsafe. Actually I'd recommend a fail safe in all cases, the only time I would not is if you have a new herpstat and enable the mechanical relay over and under alarm settings. Even that being said I one one that has these functions active and still use a failsafe.

There is a lot of discussion over this by the enclosures I have that I chose this had wild shifts before I went this way due to big room temp changes. I was seeing hot spots that shifted from 86º to 101º the t-stat was set to 100º the room temp varied too much and the probe insulated from the air temp failed to adjust correctly.