For an under the tank heater, I use a Flukers heat mat https://www.amazon.com/Flukers-Repti...er+tank+heater they are only suppose to get to a 100 degrees (mine read 113 degrees after i attached it with foil tape and had airflow underneath it) so even if your thermostat fails it shouldn't get hot enough to badly burn your snake. It doesn't have an adhesive so I used aluminum foil tape to hold it on and you will need to make sure there is some air flow underneath it. Like others have said for a thermostat like the jump start https://www.amazon.com/MTPRTC-Contro...art+thermostat is a nice cheap edition one that i currently use but the herpstats http://www.spyderrobotics.com/index....=index&cPath=1 are better and more reliable thermostats and ill be upgrading to one soon. The infrared temp gun https://www.amazon.com/Etekcity-Lase...words=temp+gun is very accurate but see on the packaging the best range, mine for example is 12 to 16 inches. Also id recommend getting a accurite combo temperature and humidity reader https://www.amazon.com/AcuRite-00611...umidity+sensor with either a probe or wireless second receiver so you can read both the hot and cold sides. Also since you have a tank if you have a screen lid most your humidity will just escape out the top you may want to look into covering the top with something there are lots of things you can use and if you search this forum you can find suggestions.