Originally Posted by LessThan5
stuff that for a joke.
Although you might be turned of by the lengthy grind to 100. I would highly recommend giving the multiplayer a fair go. If you're only going to play it to get the multiplayer achievements, it's probably won't be fun experience.
Best thing I can suggest would be to crew up and play productively and often. There are guides around the internets with quickest paths to rank 100, but it's still going to take you more than a month.
Good luck if you decide to go ahead with it