My best rough guess would be made using the weight distribution on the front and rear wheels.
Coupe % F/R 54/46
Roadster % F/R 53/47
Distance between wheels is 94.5 inches.
This would assume that the mass between the wheels was constant over 94.5”, which it isn’t.

Make a steel I beam that locates in the front and rear jack points on one side and then jack it up on one side to find at which point on the beam both the front and rear of the car lifted equally would be more accurate, do both sides and compare.