We're lucky enough to have a north-south runway, and the sun to our back in the morning. But as and instructor my students sometime get into awkward situations and I have to take control of the plane as it's getting ready to cross over the sun. I have polarized clip-ons for my glasses that do a great job of cutting a lot out, but I do something else that has kept me from ever losing sight of one. As I know that I'm going to have to cross the sun, I make a quick mental calculation of the planes path and project that to the other side of the sun. I then direct my eyes to the other side of the sun, cross my fingers and toes and wait, and hope it comes out where I predicted. This keeps me from looking directly into the sun. Hasn't failed me yet.

Hope this helps