the centerline of gravity in a rotisserie is less than 3 inches above the bumper bolts.
At least my tiger was absolutely stable on the rotisserie with axles and tires mounted at this point.
But the unloaded springs and the missing interior and top will have been working in my favor.
with the axles off the car, but engine and tranny inside it was slightly unstable... so I guess 3 inches above bumper bolts is correct.
regards, Thibaut