I feel I am going to do all stanchion lines the same way which would require 18 turnbuckles total. Although lacking in detail it does mean that there is largely less metal to metal contact and paint chipping.
I just wish there was a silver heat shrink.
I've ordered 1mm stainless steel rod for the safety line anchors rather than the brass pictured.
EDIT
It just occurred to me that I can use stainless rod on the brass stanchions too as I'll be fitting them into the accurately drilled holes with CA that if I fit one end of a turnbuckle as appropriate before gluing it will save a lot of other work. (only to the ones that have a tensioner)