use down bag with zip-open footbox
Easy compromise. Buy a Kelty Lightyear down bag with a zip-open footbox, or any down bag with a zip-open footbox. The Kelty Lightyear bags are often on sale for well under $100. Get the 20 degree model. Get the long size. Pull your hammock through the bag. Keep the bag pushed down to the foot. Get in the hammock. Reach down and slide the bag up around you. Zip as far up as you can. Use the velcro tab to pull the hood area up tight to the hammock. There you have it. Top quilt and underquilt for less than $100. Cozy warm. Ultra lightweight. The portion of the bag beneath you will actually keep you warm, compared to sleeping in that bag on the ground, where you will compress the down beneath you. You don't need a pad inside the hammock in this setup, so you won't wake up on a clammy ccf pad. You probably carry rain gear on most trips. Put the jacket and pants on as your underwear, to create your own vapor barrier, to keep expired moisture from adding weight to the bag. If it's going to be less than 20 degrees, pull some of your clothing on top of the rain top/pants. No reason why you can't be comfortable down to zero F or below. Don't forget a good warm beanie or balaclava, since the bag's hood won't wrap your head as completely as if you were tent camping in the bag. You can zip the footbox mostly closed, but if a tiny bit of air flow gets to your feet, wear socks. Keep the hammock inside the bag and compress the bag into its factory-supplied compression sack. Stows away easy-peasy. The drawbacks? you are inside a mummy bag, and can't sprawl out and get a diagonal lay as easily as if you didn't have the bag around you. To some, that's a big deal. Not to me. I'm an ultralight backpacker, and I value the ultralight and ultra affordable nature of this setup, with my Grand Trunk Nano 7 super light hammock and whoopie sling suspension with straps and sticks found on the ground for toggles.