Dava,
My sister works (15 plus years) for an insurance adjuster out east and I asked her that exact question.
Her response is that unless your policy specifically states they do not cover offroad damages, they cannot refuse payment.
Think about it, if your vehicle is parked in your driveway and a tree falls on it , is it covered? Of course it is.
Now, are for as the motor vehicle act is concerned, whats the difference if your in the middle of the bush or in you driveway? Technically they're both "offroad"
She also said most insurance companies will initially try and weasel their way out of coverage, but when pressed, they cannot refuse.
Vince