Although I also opted out on fiber glassing the body to chassis and used the pan gasket and RTV instead? I'm not sure if that was a mistake or not? It certainly would not hurt anything doing it. I've actually considered covering the entire floor and tunnel area with fiberglass mat or cloth, but never done it?
But, there were a couple of other areas to glass-in as Gordon has already suggested.
In addition to the front pieces that support or seal around the bumper brackets, I glassed the rear engine compartment to the frame, and I think the rear trunk latch had to be glassed in place also?
Good luck, that's all good stuff to have behind you.
Boston Bob E