Ah yes, the accidental 35 km over trick.
Spped camera or police with radar??
There are ways and means you can over come this. First question, how much is your license worth to you? secondly, how much are you willing to depart on the chance it could be for nothing? Pick up the yellow pages and pick out the biggest ad you can find for traffic offence lawyer. Some will tell you it's a lost cause and some will take it on. Ball park you looking between $800 - $3000
Or just contest it on the back of the fine, use no legal representation, its free.
In my opinoin EVERY speeding fine/infringement is worth contesting, weather in the right or wrong.
Think of those poor buggers that all got caught on the western ring road a few years back when all the cameras were not calibrated properly. A lot of people got caught doing just a few over (but haden't) and lost their license due to points and what have you, imagine loosing your job, your house because you couldn't pay your morgage due to no job etc...
Or just cop it on the chin, your an idiot for speeding, accident my arse.