With a special thanks to @WillAdams’ post showing his layout plan, I set to putting mine in order. I believe he used a PVC material. I opted to cut 1-1/2, 3, 4 & 6" slats of 3/4" MDF. The only PVC material I could find locally was like $60 for an 11" x 12’ piece used for facia in house construction. I don’t know the exact dimensions of Williams, but mine must be fairly close.
The MDF slats and T-tracs are screwed directly to the original waste board.
This is a dry fit of the final project. A little more sanding, a good priming, the addition of the dowel caps and the finish painting and it will be done.