Well, you could use the top of the rat guard as the inference point instead of the bottom if you want.
Since the next panel would be on top of the first, you would need to use Move to move it out. Not Rotate.
Although it probably could be done, there isn’t a tool per se to warp or stretch the model as will happen when you screw the metal down. There’s really no value in doing that. In Fact I don’t see that there’s much value in rotating the sheets so they cover the rat guard, even though it can be done. I would probably just leave the panel vertical and let it sit away from the wall at the top by the almost nothing thickness of the flange on the flashing. I’m all for precision but chasing those sorts of details is a poor return on your investment of time.