Just no time to keep this thread going but I am doing the math in the background and it's open to so much interpretation that I'm worried this thread will degenerate into philosophy and then get shut down.
So here's what I'm understanding of the present so far (and will present the math at the end). It looks like the present is an individual bubble surrounding each of us. The farther away from your bubble, the more past of everything else you see. (The stars you see now are how they looked way in the past.) Even if everything and everyone around you is in the same frame, you are not all seeing the same present even though you're all sharing the same present. So if a bunch of bubbles are all moving at zero relative velocity strung out all over space, they don't coalesce, they remain separate but strung together by a calculated common present.
Is reality what you share (calculated) or what you see (subject to the speed of light delay)? If the sun disappeared, our shared present is that we don't know the sun is gone but for 8 min our present reality is that the sun is still there. This theme of apparent present and calculated present permeates relativity but which of these is actually defined as reality?
There are more facets to this question. If the present is a small bubble and length contraction is only in the direction of motion and reciprocity exists between two participants engaged in a relative velocity, then any effects we theorize about what we would see of a ship at .6c should be the same as that ship sees of us. Currently SR says we would see very localized dilation/contraction of the ship but the ship would see the same effects occurring to us on the scale of the entire universe.
But is this really true? I'll show you my math later but for now let's just put our finger to the wind. The farther anything is away from your bubble, the smaller it looks and the slower it looks. These effects are just illusory perspective but we can calculate the underlying reality.
Let's take this to the extreme and explore where the theory comes from that the CMB is an absolute frame of reference. It is both all around us and is equally distant from everything in the universe. It is as far in the past as we can see yet we can calculate a shared present with it as well (based on whether expansion of the universe has a relative velocity to it or not). It is so far away that time appears to stand still, 0 velocity relative to everything. This is apparently true but not really true. The distance from the CMB means a ship traveling .6c relative to us will not see the universe any more contracted or time dilated than we would see the same universe around the ship.
Consider the popular version of relativity that states you can't tell if the universe is rushing past you or you're rushing past the universe. That concept, as stated, requires an implied anchor point that is outside the universe. It's like the universe is a record put on a record player and the needle is fixed to the record player while the record spins underneath it. It's like the LHC is spun around stationary protons. These concepts may be valid mathematically, but they are not valid physically. You can never consider the mass of the universe spinning underneath you in the same way you can't consider hidden stagehands moving the scenery around you like we are all actually paralyzed in space. Those concepts are not physical reality, one can always trace back into the past on who experienced acceleration to get moving.
You don't need the idea that either frame can be considered stationary, all that counts is the RELATIVE motion which can be depicted any way you want in an STD. If Alice is moving, you don't ever have to consider her as the stationary frame, that is all embedded in the STD, you just need to see it.
Here is an STD at .8c of what each participant sees of the other. The view is identical, it's just the coordinate systems that make it look different. Just like Bob sees Alice in square coordinates, Alice is also seeing Bob in square coordinates but Bob looking back at himself through Alice's eyes would see the rhombic coordinates.

The dotted lines represent the present from each perspective. When Bob is 3, he sees Alice at 1.8 her time at 2.4 ly. When Alice is 3, she sees Bob at 1.8 his time at 2.4 ly her spatial coordinate. From Bob's perspective they may age at the same rate but they do that at 2 different present times. For example, Bob is 3 at t=3 but Alice is 3 when t=5. But what if there was a perspective from which both Bob and Alice are 3 at the same time and age at the same rate. Or what if Alice and Bob had a relative velocity of .8c but had no reciprocal time dilation between them and aged at the same rate at the same present time from both their perspectives. The STD's depicting these will be developed in the next post.
Hint: a reference frame doesn't need to be stationary nor does it need to be tied to one of the participants.