Rear valance early model?

[R1ckM]

So I have a 88 325i and its got the diving board bumpers. The lower part of the rear, under the bumper. I just call it the rear valence.
It has a little rust on a couple spots and I was curious if just that bottom sections under the metal bumper was something I could unbolt and replace with a nicer one?
If not then how do people generally go about repairing rust there?

[Stanley Rockafella]

aside from cutting out the rust and welding new metal in place, you can purchase a whole new panel and weld it in place