Hey, I have also just finished the game and would like to do the co-op maps. Is the co-op all action and no stealth? If that is the case I think it would be best to just do it on casual to make it quicker. I used to do the same thing for the Uncharted crushing maps a few years back.
Also I'm from New Zealand so I'm not sure how our time zones would stack up. I'll add you later today.