Impossible? No, just unlikely.
This Superman Clarkkent ambigram is a fairly long asymmetric ambigram that is a good example of ambigram artistry at work.
See this example of how this design says 'Superman' one way and says 'Clarkkent' the other way (or is it the other way around?).
Try it out now. Just swipe the design (on a touch screen) or move your mouse over it to make it rotate.
If this design isn't exactly what you were looking for, you can create a new one using the Create New Design button located here.
Select This Design Create New Design