If I meet one of your perfectly rational agents who cooperates on true prisoners dilemma, I'm going to defect. And win. Rationalists should win.

The problem with your plan is that TDT agents don't always cooperate. I will only cooperate if I have reason to believe that you and I are similar enough that we will decide to do the same thing for the same reasons. I hate to burst your bubble, but you are not the first person in all of recorded history to think of this. Other people are allowed to be smart too. If you come up with a clever reason to defect when playing against me, it is very possible (perhaps even likely, although I don't know you all that well) that I will think of it too.