My winter Incubator had a sag under my calf on the left side back toward my hip. The solution wound up being to pull the left foot end corner toward the suspension while leaving the footbox side loose to move on the channel. I countered this at the head end by anchoring the right side corner, this kept the UQ in place. In the end I didn't need to support across the ridgeline but it's a good bandaid solution during the night and you have CBS.

David