5 & 7 (getting in touch with the researcher, via website or email) have been the most successful for me, for hard-to-get papers.
I'm not certain about this, but I believe that authors maintain personal redistribution rights in many cases, making the whole thing above-board.
Email an author to politely ask for a copy. Researchers spend a lot of time on their research and are usually happy to learn that somebody is eager to read it.
Granted, n=1 anecdotes don't mean a whole lot, but the one time I emailed a researcher like this, they not only sent me the paper I was interested in, but later sent a couple of pre-prints of some new (related) research from their group. And then even later when I emailed again asking for some data files referenced in one of their publication, they happily forwarded the data in question to me. I think this was definitely a case of "they were thrilled that somebody else was actually interested in their research". YMMV, of course.