What a super idea , I am in favor of this recognition of HG pilot's advancement from elementary gliding to sustained soaring flight. As more of the on going brainstorm on this subject progresses it will be fun to witness the full achievement of this worthwhile goal.
May I suggest , as with challenge "coins" in the military , a variety of different "trophies or awards may be included & supported , even as Joe mentioned the pilot may be able to initiate his or her own design concept for their own Lilienthal Award. In the military , such Challenge coins are handed off by upper ranks to lower as a token of recognition & achievement. So too , in HG a more advanced Pilot may prefer to present such an award or Lilienthal Coin, after a Soaring Flight has been demonstrated.
Thus a coin of popular design may be re-struck and requested for future presentations , thus opening a wide variety of art & design into this Soaring Trophy system-
Good Ideas keep coming in...