Dropped the ball - Need Help

Hello guys,

I dropped the ball big time. I purchased an '02 off eBay without doing a pre purchase inspection. I thought I'd be protected from any undisclosed damage, but I was wrong. Completely my fault.

The car spent most of it's life in the NE, and wasn't well taken care of. It showed up extremely rusty. I didn't know rust could get that bad or how quickly the costs would add up to fix it. The frame is ok thankfully, but the rocker panels are gone. I'm getting a set of these from the junk yard so they can be welded on.

The part I'm struggling with the most is the inner part of the quarter panel above of and sort of behind the passenger side wheel. I'm not sure what this part is called, but one side is completely gone. I've attached pictures for reference. If anybody has any advice or experience with fixing this, I'd really appreciate the help because I'm not sure what options I have for this section.

 

I have some rust in that spot as well and I plan to cut the rust out and just treat the remaining metal. With the doors closed, it is not in view so I can live with it.