Akinbo,
I didn't set out to resolve GR with the DFM, but when the jigsaw puzzle came together a big hole at the front of the red steam engine remained, and I had a few red bits left that fitted perfectly. Now Popper said there's no such thing as 'proof',... but I'll hazard a guess.
There are reputedly two effects making light bend; Diffraction, and Curved space-time. There are all sorts of issues with both, but if they're the same thing then all the issues are removed.
This then agrees with light changing speed at the boundary scattering zones found (shocks, haloes and surface charge/TZ's) to propagate at c or c/n in the rest frame of all inertial systems. Inertial systems can then now be real, made of matter, and as big and diffuse as we like.
Ergo; Light on a bus does c wrt the bus, when it's re-scattered at the window glass surface it does c wrt Mars (if the bus is on Mars), but that is NOT the same as c wrt Earth. It must travel to Earth and pass into our atmosphere to then do c wrt Earth (DSoppler shifted each time). if it then comes across a moving bus window, it changes again to c wrt that bus. light is then ALWAYS found at c by ALL moving observers. Paradox lost, paradise regained.
Yes, the high speed of outliers is explained. Speed is only ever a relative concept (it only ever has been). The inner halo has a rotating rest frame. the stars are actually moving quite slowly. But they may of course be moving very fast wrt and other arbitrary observer frame.
Newton's approximation is pretty good, representing the particle density fall off, but the Yukawa ('screened Coulomb') potential's slightly sharper cut off at the shock should proves more precise.
PS. I posted a question re dark matter on yours (on an an early June string). I also think your question on the question of existence was good, and raised an issue with the basis and approach used there.
I think you should be higher. I'll pass out some encouragement. Best wishes.
Peter