Gonna revive this thread once again since I just tackled this project this past weekend on my 2003 Suburban 1500. I bought a pre-bent and flared kit of SS lines. I was able to fish the rear line through the rear driver side wheel well.. it was actually not the hardest line to run. I found a youtube video of a guy who showed how its done:
https://www.youtube.com/watch?v=KHwIEwTZjnI&t=8s
I had several slow leaks at the flares when I was done, which I was able to remedy with copper flare gaskets.
Hope this helps.