5. Maybe precession has moved the stars ahead with 28 days from the time the important stars were initially connected with the days of the year? No, I think Antares initially was the  star for day 177 and at that time (around 5000 B.C., cfr at Camp 9) it was equal to the distance from Aldebaran, the star which marked the beginning of the 'summer year' - Antares marked the end of 'summer'. 28 * 72 is only ca 2000 years.

Later their proper motions gradually extended the distance between the stars and relatively close to modern times (ca 1300 years ago), Antares had begun to rise heliacally 180 days beyond Aldebaran. Nowadays the distance is 181 days:

Parallelling a gradually increasing distance from Aldebaran to Antares the precession moved the stars further into summer. But the idea of Aldebaran beginning and Antares closing the summer 'year' remained in memory, and the creator of the G text evidently designed his structure accordingly, with 4 days prior to Aldebaran in order to measure out 186 days for summer north of the equator.

Of these 4 days ('nights') only the last 3 should be counted as 'summer' (the front side of the year), because Gb8-30 should probably be like the night of Kane in the Hawaiian calendar (cfr at The Heart of the Lion), and 8 weeks beyond Aldebaran there seems to be another set of 1 + 3 days initiating the henua calendar (the season of the 'climbing bird', manu kake):