From what I recall about the roll over accidents that board members have been involved in, all of them involved hitting something that flipped the vehicle or leaving the roadway which caused the vehicle to roll. Suspension upgrades won't help in this type of accident. Driving a low, wide car will help. Even then, if you loose control and go off the side of the road, there's a high probability of rolling the car.
The type of roll over accident (single vehicle) that is reported by the gov't involves rapidly turning the steering wheel one direction and then back the other way. It's sometimes called a J-hook test due to the path the vehicle takes. It's supposed to simulate a collision avoidance manuver. I'd have to locate the report again, but as I recall, single vehicle rollovers where the vehicle stays on the pavement and is not "tripped" by anything (the type that was tested for) represented a small fraction of rollovers.