surface division

Hey guys please i am trying to divide a surface and extrude the needed surfaces by the normal of each divided surface. I want to create planks from a surface per the image attached.

I am trying to divide the opposite edges of the surface along the length by 5", 1/8", 5", 1/8"... then use the created points to create lines that i can use to divide the surface. 

How do i divide a line with the pattern 5", 1/8",5", 1/8",...? OR is there a more efficient way of doing this?

Thanks