Nothing good at hand right now, so
Open House.
Dora-9:
I haven't seen any references to American forces based in Bunderberg, so it seems unlikely that they built your hangar.
However, I have seen references to wood truss hangars made to American designs built by the RAAF at Tocumwal and Werribee during WW2. Maybe this is also the case with your hangar and could explain the American connection in the story.
Is the inside of yours the same as either of these?
Section of a 29. 3 m (96') span hangar at Werribee, Victoria
Section of the 39. 6 m (130') span hangar at Werribee, Victoria
Timber Building in Australia