I am curious how option 1 deals with the creation of the sun and the moon on the 4th day - what measured off the duration of the days and nights of days 1 through 3?
The creation of the "two great lights" (traditionally associated with the sun and moon) on the fourth day does not mean there was no division of light and darkness before - in fact, the text specifically says they were divided before.
First, it has been assumed in the conservative Reformed community for more than 150 years (on the strength of the witness of Shaw, Hodge, Mitchell and Warfield) that the Confession articulates no particular position on the nature and duration of the creation days and that one’s position on the subject is a matter of indifference. Second, and in that light, many of the founding fathers of the PCA took their ordination vows in good conscience while holding to non-literal views of the creation days or while holding to that issue as a matter of indifference. It would be less than charitable for any of us to view them as unprincipled. Third, recent primary evidence uncovered by David Hall and others has convinced many that what the Westminster Assembly meant by its phrase “in the space of six days” was six calendar days. Fourth, one hears from some the complaint that the PCA has ‘broadened’ and from others that it has ‘narrowed’ in its tolerance of positions on the days of creation. There is, perhaps, something to be said for both these perceptions since there appears to be advocacy for change in the PCA in both broader and narrower directions.
Genesis 1:5 And God called the light Day, and the darkness he called Night. And the evening and the morning were the first day.
That 24 hour day has not changed but for maybe a few seconds.