i mainly use a 32* momentum rab top bag in a ptarmigan bivy. i've been thinking about cutting the top bag into a quilt to extend its comfort range as neither have zippers. it already has a sewn style footbox, so that is straightforward.
laying under the top bag in the bivy doesn't make a good 'quilt test' because the sides don't come down right. so to tap into the community's experience, would i be losing out on anything if i did this? I don't mind pushing this bag below comfort, and as i do that often, i don't want to loose much warmth when i want it. would i then need to sew quilt straps to keep it in place and retain heat or is this not necessary in a bivy? (i don't toss too much). i'm asking b/c i haven't used a quilt before and am noticing that most quilts, even non-arcs, seem wider than my top bag.
if it matters: i use a torso ridgerest, usually inside, and a small tarp as a pillow unless i foresee rain or can't find a needed windbreak.
i read on whiteblaze that Piper a PCTer stuffs her quilt into her Houdini instead of carrying a down jacket. It's been working pretty well for me but I think a quilt would be easier to wrap than a top bag. so easier multi-use, better temp regulation and a couple ounces (unless i winshirt the fabric) is my hopes.
also, i'm thinking about order a couple ounces of down and overfilling it. any thoughts--the previous threads seemed undecided on this?
thanks for your thoughts before I wield the scissors