But.... your current jobber is 650g, and that stuff is 135g/sqm. A bivvy is gonna need at least 4sqm all in, no? That’s 540g before you’ve added any hardware.
Edit, though I suppose you are going to really trim it aren’t you? Limited movement and no lining I guess you could get it under 3sqm
Yeah that was my thought, trim it. My.current rab ascent is big, so if I make this one tight itll loose a lot.
Weight isn't my no1 concern, pack size is.
https://www.extremtextil.de/en/3-layer-laminate-gtx-extra-breathable-soft-elastic-ptfe-membrane-130g-sqm.html
Looks ideal.