The traffic law around taking pictures and videos refers to Mobile Phones, but it doesn't specifically cover using devices like a GoPro, etc. Can I use a GoPro to take video or pictures whilst driving?
As long as you are not breaching laws by what you are taking photographs of - i.e. people engaged in private acts, and you are not driving recklessly then I don't think there are any road laws in WA that would prevent you from using a gopro while in the car. The laws that relate to use of mobile phones don't seem to apply to other devices oddly enough.
BTW, stupid idea. Driving needs concentration so you are not a danger to other people. No-one's health should be put at risk because you want to record some scenery. Take a passenger along to do the recording while you concentrate on not being a danger to other people.