While it was not directly the inspiration for the coda of Breathe, I own and love this painting of Boromir in his Funeral Boat which was done by my friend and heart-sister Robin Wood. (See her work here) It was one of several cards she painted for a very early Tolkien card based game by Iron Crown, and it was done in 1997.

I burst into tears when I first saw him, dark haired, gently smiling, under the water of life. My only
problem was that he looked too young- much to eerily like Faramir himself – and that was hard for me to deal with! But I understood that Robin was showing the peace and rebirth of Boromir’s journey, and my own feeling that in a sense, Faramir is Boromir's rebirth. Later it made me wonder if Faramir himself might not be struck by the similarity when he sees Boromir’s face in the water.