Basically the title.

Do you think there's enough content in the small boxes to make a full-length campaign book?

Or maybe even add a sheet of cardboard to the book (somehow) to introduce, say, Valyndra's more-evil sister.

Again, wishful thinking, but it's an interesting thought.

I am not sure I got that question. If you are asking if you can develop your own custom campaign with components of the core game + LotW the answer is definitely yes. The is enough content for an almost unlimited number of custom campaigns in the core box alone. FFG just did that when they released Heirs of Blood. Your creativity is the only limit.