You might try a couple of wraps of teflon thread-sealing tape around the
threads each oil change. I haven't used it for that, but it might work.
A new pan wouldn't be too awfully expensive, either.

There are three ways that correct this.

1. Buy the oversized drain plug from most auto parts stores.
2. Buy the nut plate that fits in the pan from your Chevy dealer or some
Corvette/Chevy vendors and install.
3. Replace the pan.

1 is the cheapest, 2 is the hardest work, and 3 is the most expensive.

Does the plug tighten down?
I'm questioning whether the threads are stripped....

If it tightens down, go to Lowes and look in the washer
section for a big a.s thick rubber washer. You might even
have to go to a Mom and Pop real hardware store.
If it will tighten down, a rubber washer will fix it, unless
the pan is actually leaking from somewhere other than the plug.

Buy a few of the washers that fix it. Over time the oil will break down
the washer, (we are talking years though)