If you read the regulations (regs 78,233,234), they are quite vaguely written as to what should be carried in relation to Nav logs, weather and weight and balance.
As an example, if I plan to fly 60 nm, land somewhere and return on the day I would check weight and balance but would not see the need to take the calculation with me. If I had carried the same load before and knew it was within limits I would not write it out every time I flew. If CASA wanted to prosecute me they would have to prove their case. My defence would be to recreate the calculation showing I was within limits. I would suggest they need reasonable suspicion of an offence (evidence) before they can start to impound or confiscate.
The regs say the pilot has to make a careful study of weather. They do not say you have to carry the weather report. Logging on the NAIPS is recorded and in my opinion is evidence of having studied weather. By all means carry it. But for my hypothetical trip I would not bother.
The reg in relation to nav log just says "The pilot in command of an aircraft shall keep a log of such navigational data as is required to enable him or her to determine the geographical position of the aircraft at any time while the aircraft is in flight." For my 60 nm flight which I have done dozens of times I would argue I could keep that log in my head and I have no doubt I could convince a magistrate that I would know where I was for every second of that flight.
In my opinion CASA's stated ramp check requirements to carry W & B, weather, Nav Log etc are just to make it easy for the inspector. I would say that apart from name and address you are not required to answer questions.
The regulations say what you have to do, they do not say how you have to do it. CASA have listed a way of showing evidence that you have followed the regs but in my opinion lack of evidence does not prove a crime.
If you get the impression the inspector is the officious prick that some people seem to have met then the mobile phone video is your friend. Be reasonable but do not incriminate yourself. If you think you have done nothing wrong, don't do their work for them. Oh, and if you do get that video, post it for all of us to see please!