Today using the cosmology calculators available, the CMBR appears in a universe about 41 million light year radius or 82 million light years in diameter. What observations in astronomy demonstrate this was the actual size of the universe when the CMBR light appears, perhaps 380,000 years after the postulated BB event?
The CMBR observations themselves speak loudly to many aspects of cosmology including the size at the time of emission. The predicted temperature of a Planck distribution of around 3000K that is now reached us today at 2.73K establishes an important indicator due to redshift. But there is a great deal more than has been gleaned from the CMBR.
If you use the cosmology calculators and plug in the value for H0 = 500 km/s/Mpc when George Gamow developed the hot big bang model, the universe would be close to 6 million light years in radius using redshift 1100 like what is said for the CMBR today. It is very apparent that much revision in measurements took place to fit *observations* with the BBT rather than predictions made that fit nature-based observations.
Revising one's actual measurements to achieve a desired outcome is always dishonest. Science rarely works that way, though we both could argue it does happen in certain fields of endeavor.
Nevertheless, "saving the appearances" does happen in science more regularly. Tweaking a theory or hypothesis is often done with more accurate measurements. It was the accurate measurements of Tycho that was the basis of Kepler tweaking the Copernican model to fit the observations. The Ptolemy model was soon debunked by Galileo, leaving only the Tycho model and Copernican model to explain the World's motions. Kepler saw the Tycho model as ad hoc, IMO, so he tried to reconcile the problems, and did. [FWIW. It's fair to note that no one has ever debunked the Tycho model, but it sits in downtown Sillyville until someone can demonstrate reasonable arguments that justify all the fictious forces required to make the model work.]
The merits to BBT should not be limited to the work from even 4 decades past, much less 8 decades. Lemaitre (1927) was the first estimate of expansion with a higher H value of 630kps/Mpc. But he was explicit that this was a crude attempt since a lot more measurements with far greater accuracy than Slipher's and Hubble's values would be needed. When he translated his original paper into English, he intentionally left out the expansion rate work because, per one researcher (Livio), Hubble had published improved much better values.
Hubble's 1929 value of H was 500 (1929). Robertson found 460 (1928). Hubble's value was based on the crude values he got from Cepheids found in six galaxies, thirteen values from the assumption that the brightest stars has the same intrinsic luminosity, and a couple measurements in the Virgo cluster. (Peebles, pg.44).
Your post #28 mentions, isotropy of the CMBR. This was never predicted.
Any evidence this is true? There would be no CMBR if not for a high degree of isotropy. Little to no isotropy would mean Recombination would not happen essentially at the same time, thus observing it would be unlikely. [But, as you next note, when particle physicists stepped in they introduced far more anisotropy.]
Homogeneity has always been a major aspect of Einstein's GR and nearly every effort in dealing with the BB.
The inflation model developed to get around the light-travel-time problem in explaining what is seen in the CMBR today (known as the horizon problem, discussed in early 1980s Scientific American reports). Other groups developed Variable Speed of Light or VSL to explain the nearly uniform temperature and smoothness of the CMBR seen, not what was originally predicted.
The variable speed idea is a valid scientific hypothesis, but the evidence against this has grown fairly strong. If it is applied only during the first Planck seconds, then we have no way to test it.
When it comes to promoting the BB model to the public, items like what I document should be fully disclosed along with the reporting. That is why I called for a full disclosure on all the tweaks made to keep the BB model held up.
How "full" do your require? Again, I encourage you to read Peeble's book as he shows this history behind BBT, including all, or most, of the early errors. This helps show just how robust the theory is today.
Science, however, will likely never abandon BB model until a better paradigm is developed to replace it. However, all the cracks and holes in the theory should be disclosed.
I have cracks and holes in my Mustang, but it drives just fine. You'll need to introduce bigger cracks and holes to cast the level of doubt on BBT as you seem to wish to do. I hope you can because this is the exciting part to science.