Make a pounce pattern. Learn what that is.
I prefer 120 grit garnet to open up the poke holes on the back side.
It is quick and allows the best carbon throughput.
You need a solid dark pattern on the wall.
Set up a pair of ladders with jacks and a plank,
or, a swing stage. (how big is the design ?).
Buy a few hundred $$$ worth of fitches. (it's archaic, look it up)
Comfortable with decades of air under your feet ? All day ? Several days in a row ?
Hanging on with no arms ? You need both hands to work.
I don't think the internet will give you instant know-how on this one.
Can't download reality.
Hire a man.
Or, send me a PM.