I finally got the SMC rappel rings and 3mm Amsteel blue.
I just sat down and tied it all on.
I came up with the lengths by setting up the hammock with my normal cinch buckle setup. Then I ran a completely separate ridgeline that held up the netting. From there, I measured from the ends of the hammock, along the straps to where the separate ridgeline intersected.
Here's my wife laying in it:
I tied some shock-cord into a loop with a prussik on the ridgeline to hold up the netting