The whole issue arises because the auction has a strict fixed time limit

You could curtail sniping by changing that fixed time limit to something less precise.

What if the auction ended, not at an exact time, but at some unknown time that could be as much as a half hour plus or minus from the nominal end time?

I confess that I snipe every auction I enter -- even if it means setting my alarm to get out of bed at two in the morning. I always bid the maximum I'm willing to spend (sometimes more than doubling the current bid price) and it definitely holds down the damage done by the "bid nibblers" who cautiously up the price a dollar at a time until they run out of courage or desire.

tanstaafl.