There is one thing that will probably help you, and I'm sure any of the paralegal firms will tell you this if you hire them.

So Careless driving in HTA says:
Every person is guilty of the offence of driving carelessly who drives a vehicle or street car on a highway without due care and attention or without reasonable consideration for other persons using the highway and on conviction is liable to a fine of not less than $400 and not more than $2,000 or to imprisonment for a term of not more than six months, or to both, and in addition his or her licence or permit may be suspended for a period of not more than two years. 2009, c. 5, s. 41.

Key phrase is "Without due care and attention"
Basically, you don't have to be a perfect driver, and never crash, you just have to have done everything that an average driver would be expected to do.
If you were passing in a designated zone, and passing under the speed limit, then you didn't do anything that anybody else would not have done, and therefore you were not being careless.

Although it does seem like "Guilty until proven innocent" it isn't entirely.
Since the police officer wasn't there, how can he prove you did something that was "Careless" all he saw is your car off the road. Even though he is a professional and unbiased etc. He didn't see it so he can only speculate as to what happened.