Tim's correct and this applies to a concurrent thread on anodes.
Stainless wire won't work as this will also cause a reaction with the aluminium. I suspect that aluminium wire of larger diameter than the original mild steel wire would be the best solution for restoring the wings.
My car has fibreglass wings and are fit and forget and even sustained being t-boned at 85 mph by another race car years ago. The front wheel took the brunt of the impact and the wing just flexed and returned to shape although the wing stay needed a little bending to return it to its correct shape.
