you can get flexible fillers for use on car bumpers that would be usable on aluminium too, they dont have much flex but just enough so they dont crack out
If you can imagine how it would bend if someone glued it to the floor and then tried to pick it up by the handle?
And then maybe tried the same whilst putting their foot on one of the side catches.
I can knock it about a bit, but, believe it or not, I paid £85 for that battered case, so I'd rather spend some more and get something good than hammer it myself and loose my stake!
Think the idea behind filling over epoxy primer is due to most fillers being porous and possible rust problems later. I’d definitely give her a coat of epoxy, fill anything you have to and then another coat of epoxy. I’ve used JB weld for wee defects as it sticks well is epoxy but easy to sand.