Vine Sonata No. 3
That cannot be performed by anyone except Elizabeth Schumann until November 2007. Also, it is too long. It is about 20 minutes long. I was at the premiere. It would be a really nice choice otherwise.
One of the short Dusapin etudes might be good, but they are difficult. I just got the sheetmusic for them and they are a lot harder than they sound.
Carter's Retrouvailles would be good as well. Also, maybe take a look at Vine's Anne Landa Preludes, which are very short and good. Not difficult, either.