I don't have any suggestions but reading this has made me VERY happy my front door is facing north. It NEVER gets any direct sun, and though they won't last forever, they seem to be holding up

If you're thinking, "She's lucky" think again. I have a terrible time managing the mold/moss on the white porch railing!

As little as 24 hours of direct sunlight will fade some fabrics noticeably.

My glass storm door came with UV coating. I'm glad the new glass storm doors are beautiful now, not just utility. I always disliked the utility look of them.

I too have a north facing door. In the area where I live, it doesn't make much difference with regard to fading:
South disintegrates in a year; West fades fastest, East fades almost as fast; and North just takes a little longer. It is because of all the reflected light from the street. I don't hang anything outside anymore - not if I want it to last a while.