Bovine421, thanks for the suggestions. The space with the water regulator won't fit the trees you suggested, it's less than 2ft wide by 3ft long, and they would interfere with access to the house. Attached a better image showing mid-day sun, it's the front entrance to my house.
Shane: I appreciate the advice on making it something expendable, totally didn't think about that, and the regulator will likely need to be replaced in a few years. Why wouldn't you put in a vine? I was considering passiflora because of the pretty flowers.
Blueberry is an interesting idea, because the area used to be generic so-cal hedge that was full of bugs and disease.. see picture from January. I have three blueberry bushes in pots at the top of the entrance stairs, to make a "privacy" screen from my neighbor's house, but the bushes haven't grown much at all. The january photo was taken midday, funny how much my neighbor's house shades the area. Blackberry jam fruit plant maybe? Or just give up and do something non-edible, hmm.