You've mis-interpreted what I've said.
Flexible stainless pipe is indeed only to go from the car to the wheel. Stainless hardlines (kinda like the steel OEM lines) do the stuff around the car body and are the most durable and damage resistant, hence my mate's using them on his off-road racer.
OEM routed copper pipe won't work in this installation as it'll be a rather different set up - instead of two pipes going backwards, there'll be one. The front pipes will go a different route, too.
Kunifer is more durable than copper, which is why I recommended that instead of straight copper.