I was just wondering can you replace the inner wings without removing the outers? Just looking at the body it looks like you could possibly pass them up through the wheel arch.
I think you would find it impossible to attach the upper boxed section to the firewall.
Yes....,
Steven...,
It can be done - if you want to keep your perfect outer fender in place, etc.
But this is a tough one.
And furthermore - as our experts Dan and Colin stated - you would have to live with a few compromises. Especially the rear attachment points of the reinforcement box section will be hard to weld without tricks. The outer ones (where Colin's small clamp is located) - yes, but the inner one rather not.
Furthermore you would have to go with fill-in welding of drilled holes instead of the original process with a spot welder, e.g. for attaching the upper edge of the reinforcement box section back to the inner fender.
But it is doable; my friend Heinrich got it done with the partial replacement of the inner fender up to the shock absorber dome. The original inner fender was a bit crumbled due to a former fender bender but the outer one was just perfect - including hood gap.
Good luck & keep us updated
Achim