A good hammock set up weighs and costs similar to a good tent set up. Comfort is arguably better but if you go up above the tree line, inna desert, or similar, you have no choice. >>1640358>55f>>1640607>0c
I've tipped down to about - 29c/-20f, I use a hammock gear incubator with extra down, it weighs <2lbs, a sleeping bag liner (literally just the liner no bag) and blanket. I am wearing decent thermal underwear and I'm a bit of a fan of the cold tho. My friends were dying.
The biggest problems in suber cold hammock camping are
Wind across your face/just exposure to the air, not much of a problem, just cover it right? Sure but at 1-2am you'll realized the blanket/shirt/rag is soaked from your breath condensing on it, which sucks.
Depending on your set up how to keep you feet warm, without adding a bunch of sock layers as that'll reduce blood flow and make them cold. I wear a single pair and bunch up the blanket.
Shifting underquilt, sometimes when moving in the hammock your quilt will move and you get chilly so you have to fix it, or find a way to fix it (in place). Ngl this is what is the hardest to get right when first getting and setting up an underquilt. Ensuring there's no air gaps and it seals around you. Definitely had my share of cold nights before I managed to fully have it correct. Now I just clip it on and done.
It's not hard to hammock camp in the cold, but it does take a few rounds to set up properly.