I don't remember but one thing I did to make kit wing ribs fit. I remember cap stripping one once long ago. When I started drawing my own wings and going from there, I never looked back. When scratch building, that outer rib would often get remade with some extra height and the new fat one would then get sanded to match.
I preferred to cap strip that joint when scratch building too. It gives the covering a lot more area to grip in a place that benefits a lot from being wider. It looks better too. I made up a number of special shape sanding blocks years ago (they're still working today) and one was rounded at just the right curve for my 2m polyhedral's one cap strip in that joint. But you really don't need any special curved sanding block. Wrap sandpaper around your finger and use the area of finger that is shaped the curve you need. It's not critical.
The cap strip can wind up rather thin in places until you get the feel for fitting it.
It's fiddly work, but really looks good later on, and pretty planes fly better.
