If you are looking for styrofoam, I just went to Lowes today to pickup some foamboard for my upcoming PVC cage and I found instead that they have this amazing 13" x 4' sheets of 3/4 inch thick styrofoam for around $10 It contains 6 sheets
https://www.lowes.com/pd/Perma-R-Pro...x-4-ft/3014185
So attach the UTH like normal. Take the Probe and use either aluminum tape or electrical tape and attach it to the outside middle of the UTH. Then you sandwich the styrofoam and the stand the tank is on between the UTH and the stand which will press the probe tight against the UTH and provide upward heat insulation for hte UTH. The styrofoam won't burn because you will have it regulated.
Observe my impressive art skills!
Here is the product itself. The table it is on is 4 feet by 2 feet
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