Our rack is set up with sterilite 1996's, we have flexwatt on there hot sides, controlled by the Herpstat from Spyder Robotics, the probe for it is placed on the flexwatt of the top shelf under the tub. I have a $100 temp gun, I actually got from our restaraunt...figured if it checks our food to make sure they dont get to hot or cold then it must be pretty on the point as far as temp. goes.
I check everyone's temps. and humidity many times a day, I use accurite placed in there tubs for humidity, I dont leave it in there though, I place it in and leave it for awhile...read it and then take it out and move on to the next guy.
Temps on the hot side (bare plastic) are reading from 85-92.7 at the hottest part. Acu-Rite reads, 76.5 as there air temp. and 56% humidity in that tub.
Also, I'm up at the crack of dawn and going to sleep at 3AM, they all come out of hiding at 10pm, yet only go into there hot hides for brief amounts of time....most of the time enough to poop in it