Though I am far more willing to read 50k+ words of fic if I can download it somehow...

Well, it takes a few minutes, but have you used the Calibre e-book converter? I'm a bit anal so most people probably wouldn't bother, but I c&p long fics into a word doc and after I format it how I want with table of contents I convert and upload to my kindle. Takes more patience to c&p things like a 50+ part fic on a kink meme but it's awesome when you don't have to expand a bunch of comments and scroll past replies, etc.