I'd rather opt for episodes-2011.
While you are correct in that the currently established way here would be either episodes or episodes-tv, I also agree that they are very ambiguous and likely to be used for any question about a TV-show's episodes.
However, I think this is to a large degree equally bad for episodes-tv-series. Even if that is admittedly only anecdotal evidence, I feel that people indeed use that tag now and then for totally unrelated questions, likely because it looks as if it's about "episodes of a TV series" (in fact I just recently accidentally removed it from a question where it actually was correctly used, merely because I was naturally conditioned to think that this tag is usually misplaced anyway ;-)).
Given that it would also set a wrong precedent, since we explicitly decided against the use of
-tv-series as tag appendage, I think episodes-2011 would be a good compromise. It would on the one hand use an established practice from this site's tagging strategies and on the other hand it also might be a bit more specific. While people could still mistake it for meaning "any episodes from 2011", this is a less likely interpretation than "episodes of a TV series" for the
-tv-series version. (Of course this still won't guard us from people just typing
episodes... and being satisfied with the first tag that appears, no matter if it has some appendage, but this can't be prevented anyway. At least the
-2011 should make them aware of it being somehow "special", or more "special" than