I'm curious about the idea, kinda feel like it would be easy to get cold spots. I think it's easier to realise you've tossed and turned enough to get a gap with a quilt, but with a false bottom, it's fabric all over so might not be as obvious. Then again it's performance innit
Na I reckon it'd be totally fine. All the insulation is coming from your pad anyway. That's the whole point of a quilt. So a false bottom bag is just eliminating the drafts of a quilt, without the additional (pointless) weight of down.
We basically did this during El Piri using a normal Cumulus sleeping bag shared between us on a 2P sleep pad. Unzip sleeping bag and drape it over both of us while on top of sleep pad. Double digit night temps so didn't need puffy jackets or anything. Worked quite well.
Speaking of false bottoms, I forgot cumulus now has some:
https://cumulus.equipment/eu_en/down-sleeping-bag-aerial-180.html
I'm curious about the idea, kinda feel like it would be easy to get cold spots. I think it's easier to realise you've tossed and turned enough to get a gap with a quilt, but with a false bottom, it's fabric all over so might not be as obvious. Then again it's performance innit