Steve, here in Western Australia our rode traffic code states
11 . Size and projection of loads
(1) A vehicle and its load must not exceed a size limit set for the vehicle in Part 7 Division 2 of the Vehicle Standards.
(1a) In the case of a vehicle other than a motor bike, the load and equipment on the vehicle must not project more than —
(a) 1.2 m in front of the vehicle; or
(b) 1.2 m to the rear of the vehicle.
As a traffic copper of over 10 years in my time in the police here most traffic coppers applied the road traffic code within the spirit of the law rather than the letter of the law.
If the code were consistently applied within the letter of the law, offences such as carrying a certain amount of fluid in your washer/wiper bottle can be pointed at as being ridiculous.
Unfortunately in any job you have "those people" and in this case they don't see the damage they do to the overall good work Police do by being overzealous in their application of these rules.
I will however caution those that get stopped that although they will never admit such a thing exists, be aware of the attitude test, this is where if the copper thinks you are genuinely contrite and apologetic and his caution will have the right deterrent effect he will leave it as a caution. If however you start to question his judgement, argue that the law is an ass, or otherwise appear that he should have better things to do with his or her time, then the attitude test is failed and you'd be surprised at the amount of code infringements can be found
In WA we have a commissioners instruction that tells coppers not to infringe drivers carrying bicycles on the rear of their car that obscures number plates. I'd imagine that was due to an approach from a bike lobbying group. I think our States Canoeing peak bodies could be doing more to represent us when it comes to the policing of carrying kayak/ski on roofs and the wearing of PFD's (in other states).
I will add that if you are in a regional area and the local police are giving you a hard time, make an approach to the Officer in charge of the local police. Someone like a surf club captain or club president would be ideal and tell him or her about your concerns. Most OIC's of police stations are keen to keep the community onside and often do not have a traffic enforcement background so are often just as bemused at heavy handed traffic enforcement in the community. They have the ability to pull the traffic guys into line and tell them to focus on the real issues on our roads like drivers on mobile phones etc.