If Einstein's second postulate is not invoked, it is a simple matter to show that Maxwell's equations are Galilean Invariant. Doppler, apparent mass increase with velocity, and other effects are explained.
I have also noticed a limitation in the wording of this second postulate.
Einstein's second postulate: "The velocity of light is constant from all inertial frames of reference."
We have had this accepted as fact with no evidence whatsoever to back it up. Yes we MEASURE light as having a constant velocity, but that could be limitations in our ability to measure and not a feature of light.
Curt Renshaw (RCM) presents a situation where the light has all possible velocities and we are only able to interact with the one that is C faster than our own.