I use the 30 ft ropes (sold as "Lifelines" by HSS and others)for my lock on stands. The rope is tied off at the bottom and top and I attach my carabineer from my harness and move the prusik knot as I climb the sticks and reverse coming down.

You could use the 30 ft ropes with your climber but why would you do that? I bought the short rope and just store it in the pocket of my harness. That way I can use the short rope system on any tree I want and not be limited to the trees where I prepositioned the 30 ft ropes. It's simple and works well.