For mild to cool temps I've been using the WS2+HHocf+sb as bottom side insulation on the Blackbird. Only "problem" I've experienced is the foot end sliding to the left exposing your right leg and feet to the cold. Bit of pain repositioning when laying in the Blackbird. Plus it tends to slide back to the wrong alignment.
Another duh?? moment resulted in a simple fix to the situation. Using the HH ocf shock cord side tie outs on the WS2 and running the foot and head shock cords from the hammock suspension line through their respective side of the JRB mini biners that attach the WS2 to the hammock. The foot side side shock cord did require tying a knot to form a loop for attachment closer to the WS2 grosgrain loop.
Looking at this set up got me thinking (sometimes a dangerous process) of an improvement. HHocfsb v2.0. Sew a Spinntex sleeve/cover for the ocf, sew attachment loops on the Blackbird at the left head and right foot end for running the ocf shock chord through to keep things aligned. No WS2 required saves ~8oz, Spinntex is wind and water proof protecting the ocf and hammock from ground/air/splash moisture. The Spinntex enclosed ocf and sb should total up to ~11oz. The Spinntex should be no noisier than the HeatShield sb. Other option would be 1.1 silnylon. Need some critical feedback about this maybe DIY ocf "underquilt" concept.