12v DC mattress warmer (to reduce carbon footprint!)

I am an avid user of Biddeford mattress warmers . I think this is the best way to fight climate change.. keep the room cold and keep your body warm!

Pros - 1) Unlike heated blankets, mattress topper warmers cannot bunch up and super hot (less risk of fire)

Cons -

1. Bulky controllers -- Because of the 8 hour auto shut off, you have to manually access the controller every night (workaround -- use a wifi plug)

2. You can feel the heating element wires .

3. No temperature control -- There is only a potentiometer

4. I only want heating around my feet

-----------------------

I want to

1. Use 12v DC self regulating heat cable

2. Create a mini mattress pad only for the feet (your feet will be ON it, and a blanket will be ON your feet)

3. Pad it, so you cant feel the wires. Padding will trap heat, but , its self regulating...so wont get too hot

It will always be connected , no controller needed. It wont be too hot, just comfortable.

I have experience with 120V self regulating heat cables for water pipes. But, not with 12VDC, picture attached)

I did a lot of RTTF and https://www.carbonheater.us/ came up. However, I do not need the flexibility of carbon . Also carbon is NOT self regulating.

I would like to hear your opinion before I start building it.

Thanks

https://preview.redd.it/n1wk2034hqyf1.png?width=2052&format=png&auto=webp&s=506332504d37f796b652100f59fb5fcfa72c0a46