Keep in mind that the real B-17 was completely covered in rivets.... So much so that when you look up close with your face against it, there are too many to ever skin on a AH skin. They are so close that they are less than 1 pixel apart on the AH skin. You get solid lines and areas of fill.
Instead, look at it from further away. You really can only see rivets in certain areas, and often only at really close face-mushing distances and only if the light hits it in such a way to bring them out.
For example, even this high-res and rather large pic (dial up warning!) shows very little rivet detail on the frame:

Even on this very close view of a modern warbird you would barely notice the rivet detail if the sun weren't at a sharp angle causing shadows:

So I would caution restraint with B-17 rivet detailing. People seem to want to really overdo it in the name of weathering. That's not really weathering. There are plenty of other things you can do to give the skin "pop" and make it "shine," so I'd say there's no need to over-do the rivets.