"the final answer will be one that preserves the integrity of the use of "day" and also preserves the integrity of all other factual truth about nature, universe, etc"
That's the point I made, young-earthism contradicts factual truth about nature.
"The observation says that there are days, and there is nothing in the observation to insist that one think of them as other than days. "
The problem is you are reading a modern reading of "days" onto the ancient Hebrew which is completely different in meaning. Reading modern defintions onto the Bible is the first mistake in Biblical study (or study of any ancient document for that matter).
I do not think I'm reading a modern reading of "days" into anything. The literal reading says "days."
Any observer will see "days" and the general nature of the story being in terms of days.
It is only theological interpretation that enables you to say anything else about those "days." A straight-forward observation says "days." Likewise, a straight-forward observeration says: Sun, moon, fish, plant, tree, etc.