CO, when I had my rockers extended that far out, I had a lot of prob with them getting hung-up in a rock-garden type of trail. I found that I had to take whole new and unfamiliar lines to fit/squeeze between boulders.
But then, I saw how well Drty and dochummer's extended rock rails did in Big Sluice in the Rubicon, and now I'm not certain if the problems I had was due to my rockers extending those far out, or just a bad wheeling day for me...
So, something you may want to think about when you fashion the mounting brackets -- would be nice if it is possible to adjust in the future as you form an opinion on how they perform.
Otherwise they look great aesthetically -- so long as you keep em sans the uber-ghey CO Hummer signatures..