Extend clearance for a 28mm tire
In some spots, the tire doesn't fully clear the brake


I take this to mean that the wheel isn't straight, and the tire rubs at certain points in its rotation. If you spend some time truing the wheel, you might be able to get it straight enough that it doesn't rub. The advantage of this approach: you don't have to buy anything.

Another option: keep an eye out for cheap cyclocross forks with cantilever mounts.