Been fiddling around with angles myself -
From the diagrams I'll assume the 30 deg with zero load.
The ridge line is then set with the full weight of the occupant (otherwise it would sag quit a bit) then left at that length as a guide for future hangs... more or less.
Am I Captain Obvious here, or did I miss anything?
One angle I haven't come across in the angle where the suspension line and ridge line meet ... on the top side. Somewhere around 150 degrees ... ish?