Bringing this back from the dead..
Bad picture, but I finally got around to putting an underbody panel on. Was pretty straightforward. I really wanted to have a solid piece (1/4 alu) protecting the oil pan, but it seems to be holding pretty well so far. You can also see the center pieces in the (bad) pic. I'm wearing about getting the coro much closer to the exhaust manifold but there is a lot of gap filling done underneath. The car actually seems to be running cooler from this.