I dont see what you are doing as shamelessly plugging your book.
I see it as selflessly sharing information. Great information at that.
I have a comment about making both ends adjustable.
Generally, I say simpler is better.
But, I saw a video on here where someone adjusted the height of their tarp from "Stand up high" to "Here comes bad weather low". They did this by putting slack in the ridgeline and then re-pegging the bottom of the tarp.
I think adjustable on both ends would facilitate the adjust your ridgeline to adjust your tarp height. Maybe its doesnt make it any easier. I have not tried to adjust my height this way so any comments are welcome.