The 40 days part is often considered symbolic, but the time period doesn't really matter.
Can you be the sole determinant about which pieces of information do and do not matter? Let me tell you: if I had to take that "40 days" literally, I would drop the whole claptrap and take up the atheist flag. That wouldn't be raining; that would be hydraulic mining. Nothing on earth would survive, not even an "ark made out of gopher wood".
You're not facing the problem. You can't write off any of the nodes and say "well, this one doesn't matter". You cannot know what other people know unless you ask them. This project of mappi...
In this comment thread, I gave the following idea, on the topic of a method by which one might judge the Book of Mormon from a rationalist perspective:
I would appreciate feedback on this idea, for an admittedly selfish reason: I am trying to instigate in myself a Crisis of Faith. So, here are the questions I pose to you: