well long story long,i have a kelty coromell 20 degree sleeping bag, and what i'd like to do is use it as an underquilt without removing the ability to use it as a sleeping bag if i need/want to. Size wise it would work out to a full length underquilt. It is also nice and wide so it will easily cover my broad shoulders at the expense of some packability/weight but a trade im willing to make for its added versatility.
Basically i unzip it all the way til the footbox where it already has a hanging loop on one side, then i sewed a grosgrain loop on the inner zipper nylon then attached a loop of shock cord between both loops and a S biner to that. by the top, one side again has a loop already sewn in for hanging storage and then i added a loop sewn into the zipper nylon and attached shock cord again. Its easy to zip it all the way up and remove the shock cord if i want.
So then its a matter of clipping on the s biners to the suspension and making sure it can stay snug. The top of the sleeping bag already has a channel with cordage so it can be sinched up tight by my shoulders, but the issue is the footbox end. The options are to fully unzip the footbox ,make a channel and put shock cord in it. The other option is to zip it up to the top of the footbox where the grosgrain is then im thinking a mini biner attatch it to the grosgrain loop. I'd prefer this as the footbox has a semi circular shape to it and i dont think i'd want to try and sew the channel into the nylon material for fear it would rip out.
has anyone else done something similar to this? are there any problems im not seeing? i'm planning on trying it out this weekend but i think its not going to get cold enough to tell if there are a lot of gaps etc. only supposed to get to 50-60 degrees at night.