If I remember correctly, the piece of base sheet metal has cutouts and bends to "cradle" the pump assembly and filter. The band clamp goes underneath the cutouts/cradle and up and around the components. Van's supplied pieces of rubber sheet to provide cushion between the base and the components.
is the pump mount. See OP21 for the optional plans for the boost pump. Even though its drawn for the old version pump, it still works for the newer version pump too.
Tom