This idea comes from being new to the construction of diy hammocks and a bit prone to overkill.
I made my first gathered end hammock with the Walmart digital camo. Plenty strong enough in single layer, but I felt compelled to put a second layer down the middle about half the width.
So that got me to thinking... Could you run a second layer of thicker material down the middle of say a 1.1 sil hammock? It may just solve the stretch issues. Not add all that much additional weight. And maybe help everyone get a better nights sleep in an UL hammock.

Crazy or Not?