[JCampbell]

Got home tonight and started nosing around. Didn't have any 4" channel, but I did have a chunk of 4" square tubing. Split it in half lengthwise and cut two pieces at 11". Fits perfectly. I still have to mark and drill the holes for the Suburban brackets (ran out of daylight). Even though I'll only catch two of the three bolt holes, I think this will work just fine.

Granted, it's not going to win any trophies at the Oakland Roadster Show, but for a daily, it looks like it'll work pretty well. Better than running just the outers, anyway.