After some unexpected work-related delays, this evening I made some progress on the fender repair.
As can be seen above, the panel has been welded in and the seam ground back to be smooth. It turned out pretty well, the only imperfection is where the curve of the patch panel didn’t exactly match up front to back, but that can be handled readily with build primer (or a skim of filler worst-case).
Still to go on this patch is connecting it to a reinforcement/brace which runs vertically down the back of the fender, and welding the skin where it’s between the fender and door (including to that brace I just mentioned).
After that, all this fender will need is a couple tabs where the inner fender bolts repaired, and it will be ready for the normal strip/bodywork/etc phase... then I get to do it all again on the other side!
(Realistically I’ll get the metalwork done on this side, throw some quick primer over the bare steel, do the same on the other one, and do the actual bodywork on both at the same time).