As it's rusting from inside to out, moisture has obviously got trapped between the two sheets. is it a viable fix to cut away sections of the outer skin, properly grind and treat the inner skin and then fill and paint. It's seems a shame to write the off as the rest of the wings are all sound.
Or...
Is it going to be too much work and I'm better off getting some new wings?
If I go down the new wing route, which parts supplied/manufacturer do the best ones and are they usually a good fit?
Cheers[frame]