You're not missing anything, but Pants is.
Reading comprehension problem today? He asked what cars were brought in as over dogs.
Those cars were brought into the class at 17:1...
But the fact remains that even the old cars when processed under 17:1 all seem to either be close to their spec weight already, or loss some weight (but not enough to make race weigh unacheivable -- see Gary L.'s post above).
You've answered your own question. If you bring in someone at 17:1 and someone else is stuck at 18:1, 19:1 or even higher, then you've created an over dog and the folks driving the cars with extra weight are going to say take weight off me and add weight to them. It doesn't matter if they are able to lose the weight to get to 17:1... they weren't allowed to do that.
So, in the same vein, I'd suggest that you flesh out your aero policy. How will that 50lbs be doled out?
You are the guy on the ITAC who has been charged with studying the aero aspect and recommending a procedure that will become part of the Process.
Show us....
How about with the ITAC using the same confidence procedure as with IT trim gain? E.g. The ITC Civic versus the ITC CRX... same weights but not the same car. ONE car is a brick the other isn't. Is there a strong enough belief that one car suffers because of this? If so, one of the cars is at the wrong weight.
It isn't perfect. It isn't precise. It is messy. It does allow for adjusting weight.