NM cable in accessible attic - perpendicular to rafters?
I've spent several hours today reading about the NEC code regarding running NM cable in an accessible attic. I apologize if I missed the answer to this, and I know similar questions are asked continually. Because I'm going to build up the joists and blow in an extra 6" of insulation, I don't want to run NM cable through or across the floor joists. I also don't want to drill holes in the rafters to thread the cables through.
This is an accessible attic (permanent pull-down stairs) with very little headroom (around 5' in the center).
My question: Is it permissible by the NEC code to screw a 1x6 or 1x10 as a running board, perpendicular to the *rafters* (high enough to clear the blown-in insulation and be accessible, but not so high as to hit my head on the board), and staple the NM cables (there may be several) to the board at least every 4.5 inches?
Will this be adequate protection, or will I also have to screw 2x4s on edge to provide a guard "at least as high as the cable"?