I 'think' I get it.
By your pictures 'on your back' it appears that you then had the spreader NOT recessed. In the picture 'on your side' you show it recessed. If I am getting you correctly, lower compression was only one of two reasons for recessing the spreader back toward you from the actual end. The other reason would be to maximize the spread where it counts, ie., closer to your shoulders, which effectively gives you less shoulder squeeze without needing more fabric width. Now, you not only have the parabolic curve looking from the side, you also have one looking down. The curve looking down starts at the recessed spreader in both pictures, but is made to start wider at the position of your shoulders in the recessed version.
I know this is going to sound confusing but I think you have already figured this out. Here goes:
My thinking is that to leave the parabolic curve longer and use longer spreaders to get the same shoulder squeeze relief at the point of your shoulders would be more effective in providing space in the hammock while occupied, and the compression could be easily adjusted to the same force by lengthening the triangle from the spreader to the tree. Using a 36 inch spreader, subtraction of the angle from 60 degrees included to say, 50 degrees included would lengthen the triangle by 7.4 inches. See difference using c / tan C, (or side opp / Sin of C.)
I used 50 degrees included angle because using a set of scales, pulling a 60 degree included angle one inch took the same force as pulling a 50 degree angle one inch, 24 ounces both cases. Only the length of the side adjacent changed.
Conclusion, Since my crude force data using a scale in ounces shows the same force virtually from the spreader to the tree, the force on the spreader, or the side opposite should be equal too using a 38.6 inch triangle instead of a 31.2 side adjacent like i 'think' you are using. Ha, this is fun!
There are only two kinds of people that understand Marines: Marines and the enemy. Everyone else has a second-hand opinion.
Gen. William Thornson, U.S. Army