Dear Gary,
I just found an essay as interesting as original. Reconstruct a posteriori the continuity between Newton's MATHEMATICAL pioneering work on calculus and its successors, AND THEN deduce the epistemological continuity from Newtons's pioneering work PHYSICAL until "quasi SR theory", what a great idea! All my sincere congratulations! After reading your essay, it is crystal clear: If Newton had been in possession of the necessary mathematical tools, he would have reached the confines of of SR, and probably more adequately than the pre-SR approaches of Lorentz and Poincaré. As you notice it indirectly on page 6, Newton, ignoring the constancy of c for every reference frame and starting subsequently from a pre-SR definition of simultaneity, would not have exceeded effectively your equ. 10, but the SR-framework would have been potentially there.
You can also do the following overlapping: As everyone knows, Humanity already possessed SR by Maxwell's equations, but without realizing it, and, consequently, without taking offense on the pretty discrepancies between classical dynamics and electromagnetism. According to the current design, it is the need of a new paradigm following the discovery of the constancy of c for every reference frame, which is the origin of the recognition that "SR, by Maxwell's equations, preceded SR". But your essay allows a broader approach of this historical process.
In my case, your essay reinforces my platonistic convictions, that of course many people cannot share. But personally, I do not see how natural phenomena may at a given moment confirm mathematical potentialities formerly unknown by the discovery of their own consequences, if these mathematical laws and their potential extension were not inherent to the correspondant natural phenomena. But this is another story...
Congratulations again,
Best regards,
Peter