I've not been on here for a while so this is a new thread to me.
I made something similar last last year, but instead of rope I used a cable clamp at the head. The design worked ok, but it seemed like I was always fidiling with it. I have not used it in a while.
I took a look at it again and was trying to figure out if I could change from using turnbuckles to some sort of spring design. I would think a constant spring tension might be better.
Any ideas?