Based on the discussion in:
https://www.mobileread.com/forums/sh...d.php?t=347606
I've decided to move all footnotes/endnotes in the books I reformat to be just after their referencing paragraphs instead of where I usually find them as endnotes. Since I'm only reading fiction, this works well. Also, I'm converting everything over to epub3 and I can use <aside> instead of the more common <p><a> stuff (though, really, it's six of one, half a dozen of the other). And, again, because it's fiction, <aside> seems more semantically correct. For instance, Pratchett's bajillions of footnotes/endnotes are actually side comments and not really footnotes. So, having them right in the text works well.
Now, if the various readers would hide <aside> stuff as the reference material I find on it says they should, I'd be really happy. But, again, for fiction, that's a pretty minor complaint.