I've watched Brandon's video on Black Bird setup. Strap angle of 25-30*. Load height about chair height. He shows a loose ridge line when sitting, and a some tension on it when laying in the diagonal (either that or he has arms of steel to be able to flex to a 90*).
When I hit the 25-30* strap angle, the ridge line is very tight. The ridge line gets tighter as I decrease the angle and looser as I increase the angle. When I reduce tension on the ridge line, I get some sag, and the diagonal lay gets more comfortable. But since my head is heaviest, I end up with my feet higher than I like. Tightening up the head-end strap doesn't really raise the head-end, because of the ridge line. I'm going to try increasing the strap angle at the head end to see if the sag will shift towards my feet.
At the moment, it looks like the only way to raise my head is to use a tall pillow of some sort. I'm a left-side sleeper BTW.
So folks, am I over-thinking this? Or am I missing something basic?