I've been training these as well... not for rails specifically, but I hope to get there eventually. The first thing that I wanted to get down was the issue of going a little to left every time I jumped, cause when I twist in the air it used to rotates my body so much that I ended up going diagonal instead of straight forward. I eventually corrected this issue by just playing with how much twist comes from my upper body and lower body. That eventually got me going straight forward and landing where I wanted too. 7ft is currently my comfort zone going from one object to another...I have yet to try it out on the concrete, but I've been doing them successfully in the gym on foam blocks.
My main issue right now is a mental one, cause as you know you can't spot your landing until you're right on the thing you're jumping to. still working on that, where are you in your progression right now? Lets compare notes
