First off, do you really think that Srila Prabhupada was like a rock star?
He carried himself in a regal, yet very, very humble manner. You have not been around ISKCON sannyasi gurus when they were behaving in an egotistical manner? It takes a great deal of association with an acarya to learn how they act in different situations and emulate that. I think its hard to be specific because much of it comes down to when to show the abhiman, which is almost a kind of pride of carrying the emblem of the sampradaya and when to exhibit a natural humility. When showing the guru abhiman, souls who are realized will not actually feel prideful but rather it is just a show for the disciples and others. An unrealized person on the other hand will not be able to carry this out. They will not catch the big fish without getting wet. So "getting wet" or allowing our ego to run amuck in the name of representing the sampradaya is something I saw in many ISKCON sannyasis in the 70s before Prabhupada's disappearance. Those who were most senior should have known better but by 76 and 77 I saw that most were not even making a show of checking their egotism. When that was translated into the guruship of the first 11 a year or two later, it led to disaster. But the next generation of ISKCON gurus in the 80s showed much of the same attitude. Certainly there are and were notable exceptions, such as Sripad Gour Govinda Maharaja and Sripad Swarupa Damodara Maharaja and a few others. So since the above named are of Indian backgrounds it then brings up another issue, which is quite obvious. Can Westerners or even very Westernized Indians put their pride and egos aside enough to be humble acaryas who set such an example for others? How to continue the sampradaya but end the ISKCON rock star guru syndrome?