I would much rather play something less well-known that the judges won't be hearing for the 1000th time.
I just LOVE MacDowell's first Piano Concerto. Very beautiful work indeed. Look into it!
Moving away from conventional concerto format opens up a huge world of other often shorter works for piano and orchestra. Many are more "lightly" orchestrated as well, which might be of benefit to the non professional orchestra.
You may wish to consider Saint-Saëns: Africa, fantasie in G minor for piano and orchestra Opus 89. In my opinion, definitely is not an over-played work. (I think it should be performed much more often.)