Answer:
For a cylinder, the load direction could be defined locally in z, but for a hopper, the load would no longer be parallel to the XY plane.
Therefore, such a load must be divided into two components (X and Y), with the "Global related to the projected area" load direction, once XP and once YP, as well as the "Linear in Z" load distribution; see the image:
The load value may have to be converted.