While on a 2 week trip recently, I set up a structural ridgeline on my ENO. Didn't do a very good job of it since it was done with supplies on hand though. I've made a better one, and figured I would post it to give others ideas. The ridgeling is made form 3mm Samson line from APS rated at 2000 lbs. breaking strength. I cut the line a foot longer than where I wanted my hammock to attach on each end. Then on each end I tied a bowline knot with my rings, for the ring buckle support, in the loops. About an inch in from the bowline knot I tied an alpine knot. This loop is where I attach my hammock. I have Camp nano carabiners coming in the mail. I will clip them to the stock ENO line on the hammock, and attach them to the alpine knots. This way I can easily remove the hammock to wash it, or hang it without a ridgeline if I want. Never have to untie a knot or anything.
I went with the 2000 lbs. line because a bowline weakens the line by almost 50%. That gives me atleast 1000 lbs. strength. It may be a little overkill, but since my straps for the ring buckle support are 3500 lbs. test, and the descending rings are 16Kn, I didn't want the line to be a major weak link. Will put up pictures when my carabiners come in and I get everything hung up, but the drawing shows where everything is. The women in the drawing gives you an idea of how this idea may also attract ladies. Of course until the carabiners come in and everything is tested, it's all hypothetical.