Need Help Heating Plastic Enclosures

I just purchased 3 plastic enclosures and i have never had plastic ones so my question is this. can i use UTH as a belly heat source for my carpet pythons hooked to this thermostat im looking to buy at this link?

http://www.bigappleherp.com/BAH-1000...2&category=15#

please tell me what you think and if it will work. i will be putting the mat under the cages itself and not on the inside so would i need to put the probe thing on the inside of the enclosure to get the right heat that my snakes will be laying on?. i will be using either aspen or cyprus much as substrate. also 1 cage is a 48x20x13 the other 2 are 24x20x13

the uth should do just fine and yes the probe should be in the cage, almost right on the uth and make sure not to add too much bedding or it will block off alot of heat.

UTHs do fine on tubs as long as they're controlled by a t-stat. And NO, the stat probe doesn't go inside because it could be moved and cause big trouble. The T-stat probe goes Outside directly against the UTH (foil tape works great to attach the UTH to the tub and the probe to the UTH). The ThermoMETER probe goes inside right over where the UTH is, and the hide can hold it down basically in place. :)

I use flexwatt to heat all of my racks / cages.