When cutting the wasteboard slats, 1F recommends cutting them at 41.5" but that would not allow the entire wasteboard to be flattened. Even flattening the area you could reach would leave a lip in the back which would be problematic for trying to do tiled work.
Has anyone had success with just capping the length of them to the 33" or whatever the max depth would be with running a 1" surfacing bit?