Cheat: Inventory Duplication
This requires two very cooperative human players, and a Live connection.
1 // In the Inventory Lobby, invite a friend.
2 // Start the level (use 1.2 to make it easy). Have the host hand items (Rotten Eggs, First Aid, Ammo) off to the guest for duplication.
3 // With a full inventory, have the guest leave the game (it should say "All unsaved progress will be lost" -- select "Yes").