I thought copyright registration went out the window years ago? ... But a quick check of "copyright registration" on Wikipedia shows that in the U.S. some things are still dependent on it. (My thoughts about that would be best reserved for the P&R subforum.
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But the previous paragraph demonstrates one of the problems you face, SigilBear: the sort of thing you are talking about is U.S. specific, which reduces the field of interesting bloggers/articles.
There is the fact the the book you are talking about is U.S. specific non-fiction (which is tightly related to the next point) and the field of interesting bloggers/articles reduces more.
Your specific interest in getting into U.S. libraries (which I understand, given the nature of your material), and the U.S. Library of Congress, means the field of interesting bloggers/articles reducers further. Most Indy fiction writers are not that interested in this aspect - or not that I've noticed - we just want readers
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Given that you've asked this question on MobileRead, whose members tend to be computer/gadget literate enough to like ereaders and Internet forums (and many of whom are not fans of Indy publishing), and you have reduced your field further still. To the point, I suspect, of having reduced the chance of finding individuals well enough informed on this particular speciality to ... maybe zero?
It seems to me you might consider yourself lucky to get a response at all, especially one that at least attempted to provide something more useful than my observations in this post.
You may need to pose your questions on some more appropriate forum if you hope to get answers given with any level of direct experience.