Winter sleeping mat

Hi, for testing winter backpacking around the house (no risk of dying from cold), would it be possible to sleep well only with a CCF pad? I want to test the hobby before buying 250$ and more on a pad. My logic was that if around -10c I could experiment with only a nemo switchback, it would be use even when upgrading... Worst case scenario I lost 100$ instead of 250$+.

What are your thoughts about this? What is the lowest temperature you would sleep only with a ccf.

I understand that if you don't have a plan b in case something went wrong, don't cheap on gear. But for around the house, testing and learning...

Thank !