Does this sound good?

Sand
Bondo
Sand
Primer
Paint
Clear
Wet Sand

 

aslong as you remove all the rust so it dont start up again, and you can bondo that big of a hole, yes it will work.

 

Personally I would sand blast or heavy wire brush wheel, sanding alone won't get rid of all the rust pitting so it will just come back. Then you can fill in some fiberglass and sand that with some rough sandpaper like 200 grit. Then fill in with some bondo and sand down the whole area with some 500 grit paper, then a good final sanding with 800 then a couple coats of primer.

It won't be picture perfect but it will make it much better. Painting wise will be difficult cause you're clear coat is peeling, its almost impossible to match it perfect.

 

When i bondoed the rust on my rear fenders on the ford truck site everybody bitched that its only gonna come back and nag nag. Ya maybe but there hasnt been a buble in sight yet so im looking forward to see how your work comes out it will deffenetially be better than rust. I would deff sand blast kinda wish i didnt sell mine now.

 

Sleaze bag used carrot trick, bend all the rusty edges in then use a fiberglass reinforced filler like claw glass, or kitty hair, only fill with the fiberglass to almost the desired surface, that way you don t have to grind fiber glass, wait until it hardens just enough that it doesn't stick to your fingers, then carve off the high spots with a box cutter, buck knife or seriously a piece of broken glass ( great scraper, teaches that gentle touch), then fill with bondo, never use the red hardener, it contains evil . Then when the bonds gets to that cheddar from the fridge level of hardness scrape off the high spots, and smear marks, wait a few more minutes until its hard hard then sand away, if you really gobbed it on, you may want to sand the shape in while its cheese hard, think sculpture not mudpie.
And work in a well ventilated area, or what I wrote will start to make more and more sense.