Currently have 200 amp meter, 200 amp breaker disconnect (main service panel), and a 200 amp subpanel in a Manufactured home. I want to upgrate to 400 amp meter to service the home and a new shop with 200 amp. I have talked with the utility and local electrician and electrican engineers, but I want to be sure I have this right.

Meter: Cooper B-Line 342C, with extra lugs to service 2-200amp disconnects. Wire 4/0-4/0-2/0 from new meter to new 200 amp disconnect (square D Q22200NRB 200 amp circuit breaker and box with bondable neutral and equipment grounding lugs). Also tie bare copper ground from new 200 amp disconnet to the grounding rods already installed for the existing 200 amp service. Run the 4 wire in 3 inch conduit to the new shop, and wire 2 hots, 1 neutral, and 1 ground (4/0-4/0-2/0-#2 all aluminum) at the shop sub panel. Do not bond neutral and ground at the subpanel.
My question pertains to how to wire the new 200 amp disconnect with all 4 wires? Any help would be appreciated.