Heat Tape vs Heat Heat Pad

So I'm about to receive my third BP, and I was wondering if I would be able to get a length of heat tape to put under her tub rather than another uth pad, like I have my other two on. I don't have a rack yet, it'll just be one snake on the tape. She's a year old and was last measured at 860 grams according to the breeders records. My main reason for wanting the heat tape is to save money, as a pad is about $30 but I can buy a foot of 12" tape and have Reptile Basics wire it for me for less than $10. Would that be the right size to get? I've never worked with heat tape before, but comparing just the size to the heat pads I already have it's close. The heat pads are 11" by 17" and they cover less than half and more than 1/3 of the floor space under the tubs.

Heat tape is a lot more flimsy and does better in racks especially where the heat is recessed (no direct contact when sliding the tub out), for stand alone tubs that may move around, heat pad are just a better option IMO, a lot sturdier especially the ultratherms.

Heat pad should cover no more than 1/3 of the enclosure , 1/2 is too much.

I'd read a few places 1/3 to 1/2, though of course you never know where some info is coming from on the internet. I still get a decent temperature gradient in my current tubs though, about 10 degrees difference between the hot and cold sides. In that case though I could go with the 10" by 11" heat pad instead and save $10 just by downsizing.

I wouldn't do 1/2, because it's plastic and that heat travels.

What are you using to verify your temperature grad?

I have an Acurite in both tubs, with a probe on the hot side and sitting on the cool side.