Dear KhakiHeron; many thanks for your time: both for reading my essay and responding thoughtfully. Unlike you, many a reader has not been able to comprehend these new/unfamiliar concepts. Physicists keep interpreting the photon as a unitary object which leads to a paradox (duality). This constitutes a dead end so they simply move on to lesser issues that are more career advancing.
As you understand, E = mc2 gives any quantized entity (either space-stationary particle or time-stationary photon) two identities: 1) a kinetic/essential identity, and 2) a potential/stored identity.
For a space-stationary atom (say Carbon-14) its mass resides in space while its potential identity (its stored energy) advances probabilistically in time toward release (decay).
For the photon, its kinetic energy resides in time (as pure oscillation) and its potential identity (its stored/relativistic mass) advances in space toward release (reception). And release is always via an event at a point in space-and-time imitating particle impact with no particle involved.
So, any entity has its kinetic identity residing (i.e., occupying an interval) in one dimension while its potential (stored) identity advances probabilistically in the opposite dimension toward possible release (either particle decay or photon reception).
And yes, for an electron moving in space, its kinetic energy is still in time but that energy has its potential identity as a wave packet (in space) of stored (relativistic) mass surrounding the electron’s rest mass. And the wavy momentum vector of the packet interacts with the momentum vector of the electron’s rest mass. Hence electron de Broglie waves!