I never thought of this a 2-line ridgline as the tie offs do not form the ridgeline at all. Anyway...

I take the line from the D-ring (or grommet) and bring it around the tree and back to the D-ring. I then tie a quick release tautline hitch which I can use to center and tension the tarp as needed. Repeat on other side. This creates a "V" shape in the line so the suspension strap of the hammock can be attached to the tree at a higher point than the tarp line and not interfere with the tarp line.

For the hammock I use a strap and cinch buckle system. The strap has a caribiner on the end which goes around the tree and then clips back on to the strap which is attached to the cinch buckle system which has been attached to the hammock ends. For me, this allows for very quick setup (and takedown) as well as easily adjustable. (I am sure someone has made a video of this setup at hammockforums, perhaps justjeff?)

My system works for me as it is very fast and adjustable.