92runner

Well, I've finally decided to repair the rust damage in front of my rear wheel well created by the stupid trim piece capturing dirt,etc. back there and not cleaning it out until a few years ago. Last night I ground out pretty much everything I could and left a nice big chunk of metal missing. My plan at this point (since I'm cheap ) is to use a metal filler in the giant hole that has been created and then fab up a sheet metal cover with countersunk screws on top (so the door will still close) and screw in from the back for the bottom portion. Unfortunately, I need something to screw into. So my question is: Has anyone used a metal body filler that they would recommend? JB Weld, etc.?

Also any other ideas for the DIY repair would be great. Thanks.

Scott