I achieved the 5 blackout trophies in just 3 weeks, around 85 hours of play, I played with 1 friend, we were on different teams and met the requirements, we made the characters in the following modes
Alcatraz: Bruno, Diego, Shaw, Dempsey, Takeo, Nikolai, Richtofen and Menendez.
Hot and Heavy: Reznov, Woods and Mason
Quads: Scarlet.
We used the Helicopter Glitch to unlock Woods and win all 10 matches.