The Driver Station shelf has to be less wide than the wall, as it folds flat to the wall when traveling and has to fit between the two Driver Station Supports. The Diamond Plate wall laps over the Driver Station Supports to make a solid wall on the field side. Sheet FE-00004-1 is an elevation of the wall from the Driver's side.
Again, study carefully the first 8 or 9 pages of 2016BasicFieldDrawings.pdf. The Game Manual may give proper dimensions, but the 2016BasicFieldDrawings.pdf gives all the dimensions to build the field.
By the way, the AndyMark field they sell is similar to the FIRST field, but assembles faster because all the pieces are pre-assembled. The Driver Station wall takes longer to explain how to assemble than to actually assemble.
Well, a little googling got my answer: back in 2005 Andy Baker
started a CD thread about a wood version of the field itself, with a nice PDF link.