First picture looks great... DO IT!! There, that takes care of that
I think if you do any rear end trim at all you should do upper and lower. I think it looks right. It's how these perfect beauties came, after all. Nybe do a mildly custom yet looks like factory coulda or shoulda done and paint the tailgate white the way a deluxe 2-tone would be. Take some of that white it's wearing on it's head and put a little on it's a...butt.
My first truck was an all ochre Highlander short Fleetside with upper only trim. That would look good with white top...and that white tail