Paint finish

If you have a auto parts store in your town that specializes in paint and body supplies or you have a personal relationship with an auto body repair shop. Stop by and asking then what they would recommend using? My initial thought would be a product (wax?) on the whole door to bring its color back to what you found behind the sticker. 

Unfortunately, sun fading on the paint around the decal is hard to restore. With the decal off, that paint may eventually fade to match the other paint, but I am not sure if it will or won't. When I was in the Army, I had window decals for the posts at which I was stationed. We had that vehicle about 14 years. When I finally donated it, I removed the post decals. The area under was shaded so the original blue band at the top of the windshield remained blue but the rest of the band had really faded. Like the gel-coat, there is no real way to fix something like that.

Of course, you could put another decal over the spot and call it a day.

I'm glad you got it to look the same. I use Turtle Wax Ice on the truck and the R-Pod. It seems to work pretty well.