Rich, in theory yes, in reality probably not.
In accepting you premium, they would also be accepting liability of an already modified vehicle.
In the event of an accident, it is unlikely that the averge Joe at the body shop who will make the initial assesment will have the faintest idea of the type/sva approval regs.
As chris has said, an assesment of damage would not be that detailed.
You have a fair point though.
If you had an accident involving the fatality of a pedestrian, the vehicle would be certainly be inspected more closely.
At the end of the day though, it would have to be shown that the fatalaty, was a direct result of change or changes made to the vehicle.