Sheetmetal work - compound curve

I've decided to tackle the rust around the rear window on my Duster. It's a pretty common problem and I've found that the rear seal was pulling away from the lower corners causing water wick between the seams and rust out the ledge almost all the way down to the tail lights ( under the seam sealer ).

I've started cutting away at the corner and a little up onto the top edge of the quarter panel, BUT right at the corner is a compound curve...top quarter panel is concave, where it wraps down into the window opening is concave, AND where it transitions to flat is also concave. It's like an S shaped banana

What is the best way to make a piece that goes there?
1. Bend and hammer it out of a single piece?
2. Bend each concave piece and weld the pieces together?
3. Bend one piece and cut relief notches to get the additional curvature then re-weld the cuts?
4. Something I haven't thought of?

I've done this before and used option 3 but it's very time consuming to get it to look right after all of the cuts have been closed up, just trying to get some advice from any Guru's out there.
Keep in mind that these are smallish pieces so I'm doing it all by hand...and it's taken me 4-5 hours just to come up with rough piece to test fit