Here's the next piece of aluminum for the interior, marked and drilled. This took a bit of care, because there are some places where frame members get in the way, and I wouldn't be able to get a drill or a rivet gun in there. You can see a few places I have colored out to remind me not to mark for holes there.
And here it is riveted into place. For an example of places I could not reach with the drill, look at the lower edge of the panel, closest to the floor pan. The two black steel tubes that form the X shape kept me from putting rivets at the very front and rear - about the first and last three inches.
Overall, a very satisfying day. It feels good to be unstuck, and putting pieces on the frame always feels like real progress. All the side sub-projects are good, but not as good as actually building the car.