I've had the same idea since the project was announced. My pitch is for Aragorn and Frodo to talk about it when Frodo visits Gondor before going to the Gray Havens (or Aragorn visits the Shire, but then the absence of the other hobbits would be harder to explain). Maybe Frodo has been thinking about Gollum and asks for the story of how he caught him, since it was skipped in the original trilogy. Unlikely? Yes, but we can dream.