Problem with the shelves is that they won't fit in the pantry with the shelves intact. As designed, the shelves are attached to the back board from the rear. Thus I can't screw the individual shelves back in place given the tiny space behind the back boards in the pantry.
Instead I decided to add supports to the back boards, under the shelves. The supports will be screwed in from the rear. Then after the unit is installed I can add the individual shelves from the front.
Out of concern that the full shelves were too heavy to attach solely to the wall, I added support legs.
Sunday morning I ran out to my local hardware store.
I picked up 12 feet of 1" x 2" board.
I cut out 12 boards, rounded the edges and stained them.
Then I went on vacation.
First the legs:
Then mount the back boards to the wall and the legs:
Then add each shelf, screwing the supports from the bottom: