As you mentioned, SSAC and transient modes both account for the internal RC effects. The values depend on the design; the reported bandwidth is including for both RC and transit time. So if you are interested in sepearating each (e.g. in the format of tau(RC),tau(transit)) you would have to rely on the analytical models, and values used/reported in simulation. For example for transit time, the mean length and carrier velocities will be needed in your assesment.