What about a contest where the designs were sent to some judging location, such as StarDock, where the designs were judged and awards of some kind were dispensed?
That seems like a good idea.
In what way can that be at all construed as being an appropriate measure of a vessel's design-based performance? That kind of format, in fact, misses the mark entirely.
It would be, in essence, purely a beauty contest. It would have nothing at all to do with how well-configured a ship is, performance-wise. Which is part of the problem with the ship designer as it is. You could conceivably make a ship that is literally physically impossible to function, and it would have precisely zero impact on its usefulness in the game. I'm all for abstraction, but that's just ridiculous, and shouldn't even be a possibility.
Regardless...that's just the way the game is, and it won't be changed. And there actually probably will be at least an unofficial contest of sorts for "best looking" ship. It's sad, but c'est la vie. After all, don't want anyone actually having to put practical thought into where they place things because it might actually matter.