Noob here...
Why the carabiner on the second strap? If it has a loop, why not just run the webbing through that loop like the first?

On the Hennessy Ridgeline...
Cut it, attach ultra small carabiners, (it's not load bearing), and build an adjustable ridgeline with the piece you cut out and a piece of larger cord using Prusik knots. Unless the added weight is an issue.