"I would suggest you ammend the rules to include the ability to post WIPs in your own galleries then (eliminating anonymity completely) or the ability to take existing renders, change something-anything-and  rerender it as new to be able to submit it."

I'd have no problem with this - especially if you HAVE to label it as a WIP for the image.

As a side note I CAN tell you one bad reason not to post WIPS (even though they do it as standard on CGTalk) is because someone else can take what you're planning on doing and take it much further.

Yes, then you're getting into people whose sole mission is "winwinwin" but hey - it's always been a thought of mine in the back of my head.