Finished my sock/undercover. not sure what to call it since I can add/remove insulation out of the pockets.
The suspension is basically the same way as a yeti works.. Hooked the shock cord to the head end on the whipping. Then at the foot end currently I have loops on each side of the shock cord (its not tied together) A mitten hook is on the line that come out of the whipping - I hooked the 2 loops to the mitten hook. A channel at each end with shock cord to seal it up.
Footend sealed up