I think this is a great idea. I may finally submit something, although I haven't actually sat down to write fiction in a while.
However, I'm not sure such a short submission time on the deadline is the best option in kuro5hin. Specifically, I'm worried about the effect on the queues.
We are not talking about a normal contest, where people put their work in large brown envelopes which will wait patiently for the judges to go through over the next couple of weeks.
This is a website with a relatively instantaneous submission process (to the edit/vote queues at least).
I have had the chance to see the process of a very small fiction contest of the traditional kind, and the piles upon piles of envelopes created by an even nominal participation are no joking matter. It is not rare, even if there are few participants, to have multiple works by the same author.
Here the works would not sit quietly on the desk, they will not arrive smoothly over a period of a few days. They could rather swamp the edit queue, all arriving on the same day and staying on the queue more or less the same period of time. Blocking a system which is used by this community for more than storing works of fiction to be judged.
I don't know if there is no limit to the amount of stories the queue can hold for public inspection, but even if there is not, there is a limit to the amount of attention the public will give to a large list of items to be inspected. It can become either a technical or psychological DoS attack on the queue system.
Deadlines are normally used in literary contests to draw a very firm line over which works are accepted before a procrastrinating author insists his 300 page masterpiece is almost ready 3 days before the winners are to be announced.
Here, however, you're asking people to submit only over 24 hours. The deadline is also a trigger for a flood of submissions to the queue which will become a problem for the kuro5hin site in direct proportion to the success of the contest.
I suggest extending the "submission time" over 3 or 4 days. There's no need to even extend the deadline, just announce that all fiction submitted in the last 4 days before the deadline will be considered part of the contest.
That way, even if this is surprisingly successful, the impact on the queues is spread over 4 days and, even if there will always be more late submissions than early submissions, we could expect a lesser percentage of the queues monopolized by fiction.
Freedom is the freedom to say 2+2=4, everything else follows...