I am looking at building a 3-Layer Sleeping system and want it good down to 20F: parka/pants + mummy bag + bivy. Planning on sleeping under a tarp.
Wondering what people would recommend as far synthetic bag and bivy. I am a side sleeper and not interested in quilts.
Ground Pad: GG NightLight Sleeping Pad + ThinLight 1/4"
Parka: MontBell Thermawrap Parka
Pants: BPL UL 60
Bag: ? how much does a Thermawrap extend a bag
Bivy: ? no idea on this one
For 20F conditions backpacking I currently use a WM Ultralite and the pad setup and find it true to its warmth rating.

