Blinky.
The fix that Kedron has done for me is legal as per the requirements from the main roads as it is not obstructed from 20L/M from behind nor obstructed from the 20L/M at the 45% angle of sight and is within the 1.3L/M height limit on my van.
Have you tried moving your spare's apart?
The only problem that I may have is if the Main Roads measure the van length, this then would raise the issue of where to mount the spare wheel, if it is deemed to be over length.
Kedron are at present seem to be installing the bracket to new vans.