Rear quarter rusting out (pic), what are my options?

My cherokee is surprisingly rust free over most of it, only small really manageable parts.

Till yesterday when I pulled off the rear plastic bumper caps. And found this







The other side is just as bad.



I was going to just cut it away.... but I am looking for a rear bumper right now, so that plastic covering won't be there long. And I still want my jeep to look good.



What can I do with this?