I'm happy to say that the deckplate mod won. I've heard some people had problems with that in the past - not from actually failinig emissions, but rather from an extra-anal tester.

I put the deck plate back in last night, so I could give the check engine light plenty of time to come on if it wanted to. The guy testing didn't even give it a 2nd look. I also thought he might ask what the thing was next to the gas cap (the extended rear diff breather), but he didn't even blink at it.