I have a first-generation Dura Ace sidepull brake on my Austro Daimler Vent Noir.

The front wheel has a fender and a Son Edelux II, both of which mount onto the brake pivot bolt through the fork. The fender and light mounts are thick enough that, with everything on the bike, the brake pivot bolt isn't quite long enough to go completely through the nut on the back of the fork.

I had to remove the concave washer on the back of the fork. But even now I can only get maybe 5 threads of engagement.

So: I wonder if I can replace the pivot bolt in the brake with a longer one.

1. Is that possible?
2. Where does one buy a longer brake pivot bolt?
3. Is there another solution I haven't considered?