I'm looking for a shrub/tree for my backyard?

Why not plant something that is not so long lived,like sunflowers. Line up 2 or3 pots in the area you want to screen off, fill them with soil and plant some seeds. I did a variety of chili pepper plants this way for the same reason. They didn't get as tall as I wanted' so I set them up on a 2 foot tall bench.This turned out looking good, I ate some of them. They lasted until they froze. When I moved to another place I simply scattered the potting soil on the yard, all I had to take with me was a few empty pots.