I am same height (abt 15lbs heavier, tho) and went with what Dream Hammock suggested for me for a 10-foot hammock, which is 64" width and made with Robic (now MTN) 1.7. I like the shorter hammock because it can be hung in slightly tighter spaces than 11'. I now have several hammocks, of course

including some 11-footers but that first DH (Darien) remains my favorite.
Since then, I've used that 10'x64", 100" SRL 'formula' with some netless hammocks (TreeRunner from SLD) made with Hexon 1.6 and to me they feel just about as good and 'locked in' as that original DH.
Also, I don't think anybody mentioned it yet but you might try changing your lay direction. Just a few nights ago I introduced a young guy (also 5'8") to hammocking using one of those 10'x64" TreeRunners I mentioned and right off the bat (without telling him my lay preference) got him to try both directions and he ended up preferring head right. He tried switching during the night but in the morning he found himself back at head right.
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