Narrow wheeltrack is always going to need stiff suspension to prevent the body from rolling too much. Trouble is, the suspension doesn't stay that way forever. How many of us have changed from factory saggy springs?
When you take a car like ours - which already has its CofG above the axle line - and then not only give it a suspension lift, but a body lift as well - the CofG towers over the critical point.
That point is (look at sports cars) at or below the axle line. With a CofG below the axle line, it becomes extraordinarily difficult to roll the vehicle. It needs a wheel to actually stop in its sideways motion (and not break) for the car to flip. Look at Porsche, Ferrari, Lotus, Lamborghini, Jaguar, McLaren and the higher-ended Renault, Peugeot and even cars like the Skyline, Soarer, Sylvia, FTO, GTO, GT40 - the list goes on. The CofG is low for stability.
What we do with our cars with a suspension lift is raise the two heaviest components in the vehicle - the drivetrain and the body. A body lift cranks up the pressure even more.
That's why the standard limits for these exercises are fairly low (50mm suspension lift etc). Within those limits, the CofG is still close to factory. Whack a 125mm lift or more and you've significantly raised the CofG so that as a lever goes, it's quite effective in reaching over the axle and thus tipping the vehicle over.
As for the Carry/Sierra issue ... I really don't know how they ever managed to put them on the road. I've seen a few of the older Sierras around town and they look great - they've had almost the entire wheel sitting outside the factory body and great big flares added to give them stability, but I'm sure they'd be capable vehicles on the lunar surface with a small change in propulsion!
