Bryce, Kifaru makes a 2 lb synthetic insulated sleeping bag rated for 20F. Interesting that a Vegan can't go with down, as I thought geese were not killed in acquiring the down. So they are? Anyway, about the Kifaru Slick bag.
Look for standard size slick, +20 F
Amazing, eh? They use Climashield. Here is their description:
The shell material used in all of the bags is a proprietary fabric called RhinoSkin™, which is an ultralightweight ripstop fabric that is only .9oz sq yd, and comes with a DWR coating. It is a little lighter than Pertex Quantum, yet was proven 2-3 times more puncture proof and tear resistant in testing. The bags will be Foliage Green on the outside, and Camo Green 483 on the inside.
The insulation used in the bags is Climashield Combat Insulation, which is the Berry Ammendment Compliant version of their XP insulation. It is a continuous filament fiber synthetic insulation that has all the properties we were looking for in an insulation. It is very compressable, very thermally efficient, and does not need to be quilted, laminated, or glued to the shell fabric. It also has excellent drape, allowing it to conform naturally around the body
If you get their compressing sack, it's another 2.5 oz.