Maybe it's ironic that someone who goes by the name of "The Reverend" is working on a Holy car. Holes in the rear quarter panels, in the floor, and just general rust problems on the car make any religious joke easy.
To start working on the good, the bad has to come out first. I removed the carpet and started going through the car to clean up pretty much every bit I could. I was worried that the rust problems weren't just limited to that spot on the inside. It was also possible that they could have made their way to essential parts of the unibody, but it appears to be limited to this one spot in the floor and then the other bits of the body panels. Plans to patch-weld in new metal are in the works and soon they'll be repaired, recoated and repainted.
In the meantime, I've managed to use an old license plate as a makeshift cover for the hole on the inside. The duct tape seal around it isn't the most glamorous fix, but it gets the job done until repairs can be made.