Yes, the line would have to be captured on the dowel so it does not slide, but I agree it would work best as shown. It is probably heavier than the webbing, I need to check.
Any ideas what the load is on a guy line? Some line I see is rated at 250 pounds. Some people use mason's line. I have not seen any rated over 35 pounds.
I will make a prototype next weekend and load it to failure.