Sounds like you'd need at least the same amount of wattage, or more, than what your CHE is. Reptile Basics also makes larger, higher wattage panels, or you can use multiple of the one you found.@Tom I just tried the link you provided and it says that they are out of stock. I found a Repti-Therm RHP that is 40 watts. Will that get a 6’x3’x3’ closed chamber up to 80F the CHE I have currently is struggling to get to 75F.
Adding some insulation to the outside of the enclosure might also help. I had to use 1.5" rigid foam around my closed chambers in my cold garage.