Fuel Filler Neck Grommet Replacement

IMO, you should drop the tank, clean the hole, and install a new grommet. I wouldn't fool around with more epoxy sealer. When you say you scratched the side of the car, do mean the inside of the trunk?

I've only done this once, but I removed the 3 screws attaching the filler neck to the body. Then remove the screws attaching the filler neck gasket at the trunk. Then partially drop the tank. Now you can wiggle the filler neck loose, and drop the tank. It was pretty easy.