Dear Dennis Crossley,
I enjoyed you essay and agree with your major premises. I particularly liked your statement, "'equivalence' really means equivalence" and I was unfamiliar with Reichenbach's explanation that F = 0 is simpler!
You ask how we might make progress toward a microscopic model of gravity. I suggest that to do such we must focus on local rotational aspects, ie, gravito-magnetic effects versus radial or gravito-electric gradients. This also has the desired result, from your perspective, of providing non-linear self-interacting action over small closed paths! It leads to soliton-like 'particles' of the type you propose.
While I agree that light is a mystery, I tend to also agree with Einstein that "there is no space empty of field" so I therefore tend to think of gravity as the least medium that is conceivable, versus the 'geometry' in which Reichenbach's F = 0.
Our conceptions thus differ somewhat on the surface, but we do agree on specific details: 1) 3D space is a dynamic continuum and 2) elementary particles are the result of non-linear self-interactions propagating around small closed paths. And I strongly agree with your take on the 'virtual particle' model of force in QFT, and on the non-sensical nature of strings.
Like you, I did not have space to develop the soliton-like 'particles' in my current essay, and I ask you to merely assume their existence. Based on such, I hope you will ready my essay, The Nature of the Wave Function, and I would very much appreciate any comments you might make. And since I think my model agrees with your theory, if you do like my model, I hope that you will give me an appropriate score.
Good luck in the competition,
Edwin Eugene Klingman