Qld RWC requires wheel track to be no greater than +/-25mm from standard factory wheel track for an independent suspension vehicle and +/- 50mm for a live axle.
If the spacer is designed and install by the factory and is built into the drum or hub as part of the design it is ok. Also if the wheel itself has a spacer cast into (alloy)or welded onto (steel) and does not exceed the above factory figures +/- this is also ok, the 12'' clubman wheels had a steel spacer welded to them from factory.
Also some early Porsche 911's had non fixed spacers from the factory technically legal but what I call a grey area.
This may have changed since I last read the ADR's, but I would be surprised.
Mini/moke wheels are centralised by the chamfer on the wheels and nuts this also hold the nut tight.
The smaller spaced drums were used on mokes and clubman's, if using the smaller spaced drums it is very important to use the correct wheel studs. Don't laugh I have seen plenty that haven't.
As for PCD they must remain as per factory even when brakes or axles are changed so for the mini/moke 4''.
It is possible to have an approved engineer redesign the hub and blue plate it. Or you can have drawings made and send them to Qld transport Brisbane with the correct form and money to be assessed directly.
Also note that normal blue plate inspectors cannot do this approval it must be an engineer.
Many years ago people were fitting Holden etc wheel to the mokes/minis, the PCD was metric, while they fitted to a fashion the studs were bent in the process, this caused wheel wobble issues and wheels coming off due to snapped studs but not as often as you would think.
Hope this helps and my memory is holding up
Darren