Fiction Adaptation Unit: Pre-Production - The Subconscious

I've been thinking about whose mind we are inside during the black-room segments and to me I want the audience to think it's the Soldiers mind that is the black room.

Upon scripting the final two lines of the film I had an idea:

"Silence and safety, and the veils of sleep.
Then far away, the thudding of the guns."

I picture this as the Narrator speaking directly to the camera in the black-room. But that proposes a problem:

The black room is the Narrator's interpretation of what the Soldier was thinking of. Any thoughts that the Narrator believed the Soldier may have had are shown in this room.
Essentially it's one person trying to think of what another was thinking.
The Soldier however, as suggested in the poem, is now dead by the time we get to the final two lines.
"But death replied: 'I choose him.'
So he went."
'So he went' sounds like death has taken the Soldier with him now, implying that the Soldier has succumbed to his wound(s).
If the Soldier is now dead how can the Narrator be thinking of the black room? If it is the Soldier's mind then it now ceases to exist.
So where is the Narrator?

My idea is that this final moment in the black room is now the Narrator's mind. Alone and with the Soldier's thoughts no longer accessible: the Narrator is finishing his thought. This 'new' black room is the transition between daydream and reality.
An example that springs to mind is a hotel: the rooms are the thoughts the Narrator has of the Soldier, the Lobby is the 'new black room' or transition, leading to the front doors and back out into reality.

There will be no hints or suggestions that the final two lines are said in the Narrator's mind.
I don't think that it will cause an issue as it doesn't detract from the film: if the audience doesn't think of who's mind the final black room is they're not going to get any less out of the film.

If you want to be very technical about it; then technically every black-room segment is inside the Narrator's mind but those are his interpretations of the Soldier's mind so I don't think it can be counted really!