I can email you the m4b, or put it somewhere on the www. DropBox perhaps? Just let me know.
As I have to store the AudioBooks somewhere on my PC, it might as well be Calibre; so the extra effort in the other steps you suggested doesn't appeal to me.
I have found that it really doesn't matter how I set the series information, as this is not visible in iTunes anyway (as far as I can see), so is only of use in Calibre where it keeps the AudioBooks and parts together.
I also find that, perhaps my own mistyping, after copying AudioBooks into iTunes, I usually have to amend the Album name so that the parts of the AudioBook come together as one (and shows as the "Book") - screenshot illustrates.