This is a combined effort, and it may seem a bit difficult. Giant Meat can only be found from defeating officers or opening chests, and that may put you at only getting like one to three from one stage. Thankfully, you'll have other things distracting you through your time working towards the Platinum, so if this is the last you have to worry about, just play through the Main Log and make sure you deal with every Officer, open all of the chests you come across, and you may be able to save face by clearing it in a matter of sweeps as opposed to playing the game repeatedly just for this one trophy.