lookin good shug.i,also inspired by fourdog,did some testing along these same lines.i cut a hole in the foot of my -20 deg synthetic bag.then resewed the insulation back in.i added a drawstring to close up the new hole and a sleeve of about a foot long then another drawstring.the bag is normal length so i reasoned i would not be able to close the drawstring tight as it would not be near the end of the hammock.so i put the extension on so i could put a sweater or something in it to close off the hole better then use the other drawstring to keep that in place.that worked good. i hung the sleeping bag upside down then tucked the hood in by my chest.i added two grossgrain loops one on either side off the neck opening and hung it like a underquilt at the front so it would not fall off when unzipped. i worried the insulation on my chest area would get compressed due to the bags weight so i added a grossgrain loop there and attached it to the ridgeline using some shockcord and a mitten hook.hope that makes sense.
i slept in this a few weeks ago,it got down to 4degf woke up to the start of a blizzard.useing my clark and small clark tarp.i was wearing light poly long undewear top and bottom,wool sweater,wool hat and fleece baclava.no socks,no aditional blankets or underquilts.was toasty warm.i like to curl up though and was unable to do so without my knees getting chilled from compressing the insulation were they touched.so if i get a bigger bag i will use this system for sure.need more room.
thanks for the vid.