- (void)navigationController: willShowViewController: animated:
inside this method you have to create custom IUView with frame rectangle = CGRectMake(0,0,0,0),
then create custom UIBarButtonItem, init it with custom view (use your previously created UIView), and then replace your rightBarButtonItem for coming ViewController with your new bar button item.
Btw. Why does it have to be such pain in the *** to go through such a simple tasks?