I would look at what you are trying to achieve here.
What is the rationale behind all the intermediate floor requirements? Two main culprits spring to mind:
- fire from below, and
- smoke from above.
Smoke from above
Intermediate floors pose a greater risk to occupants because the smoke plume can generate a smoke layer that could engulf the occupants much faster than if they were at ground level - intermediate floor occupants generally are escaping in the “hot layer” for a short period of time.
If your packing shed is a high roofed space, then the 1.5 m platform would be of no consequence and should not be considered as an intermediate floor in the context of smoke layer tenability.
Fire from below
Fire rating the floor and walkway should be a consideration based on potential fire load under and ignition sources. As Geoff has already stated the likelihood of occupation of the space is high.
For me, the threat is fire from below; not smoke from above. Unless you can physically prevent a fire load and ignition source beneath the elevated structures, fire rating the floors would be a really good idea.