Try prickly pear cactus.

We live on a 80x100 ft. lot Our 6 ft. 'privacy fence' doesn't do a thing for us to the East as that our neighbors are on elevated ground. We have used the 'layering' method with espaillers on the fence and a walking path between the next row, much like an alle, to create a visual barrier which works well in the late spring and summer months when we are out in the garden alot. Come late autumn and winter, our privacy 'screen' gets pretty scanty/leaf bare. We've also strategically placed two fast growing, large, evergreen native shrubs within the rows of edibles. They aren't edible but the berries can be used to make wonderfully scented candles. Most of the things we have planted in their 'view zone' will not get overly big to block their sun but will block their view into our garden (not that I don't want to share ... I just don't want to live in a fish bowl!)