Problem is that "guitar string tight" is hard to quantify. I set mine more like a washtub bass.

Barring stretch, as long as the ridgeline is taut the hammock lay should feel the same regardless of hang angle. Hang angle does affect the tension in both the ridgeline and the lines to the trees, though. We tend to gravitate () to a 30* angle because that sets the tension in the suspension lines at about your body weight. It's the ratio of ridge line length to hammock length that affects the lay more. Somewhere around .85, give or take, seems to be the going number.