Do you rub when the tire is straight?
Do you rub when the tire is turning but not flexing up?
I believe the 2" spacer is your issue. When you put on a spacer the radius of the tire location in relation to the fender well changes significantly when turning. You essentially have moved the outer radius of the tire closer to the fender well. Remove the spacer and see if the issue still exists.
my 17" wheels on 35's had 4.25" of backspace and no rubbing issues with aforementioned mods. Well, it did rub when flexing up hard over whoops. some have gone so far as to cut out part of the fender well and weld in a new piece of metal. I am shocked a 33 would rub with that much lift. Again, I bet its the spacer.