I didn't know the cameras captured infrared light.
On that basis you could position infrared lights to create over exposure in the vicinity of number plates and the rego label.
That would be illegal - it's specifically prohibited to use any methods to interfere with the function of speed cameras, radar etc.
Are you sure?
Every person commits an offence who—
(a) uses in a motor vehicle any equipment that interferes with the operation of a speed measuring device:
(b) possesses in a motor vehicle any equipment that is designed to interfere with the operation of a speed measuring device.
If the camera can still measure speed and snap off a photo are you interfering with its operation? It's still operating normally, you have simply changed the external conditions.
It is illegal to obscure your number plate but IR illumination is invisible so your plate is still clearly legible to the human eye.
Note: I wouldn't actually bother doing any of this - cruise control is a much simpler precaution. But I do enjoy thinking about it.