Nandina makes a decent hedge. You keep it at a manageable height and keep it looking fresh by getting in there once a year and selectively removing the oldest, tallest stems. It can reach the eves of a 1 story house eventually. Disadvantages is that It spreads by rhizomes so you have to keep it in bounds root-wise, and if you don't remove the old tall stems you get a bare base and a tall plant arching outwards. Eventually kind of scraggly. With yearly maintenance it can stay pretty. Ignored it can get pretty sad and taller than 4'.

I like Nandina 'Firepower', though it's not going to get 4', more like 2'. It's really well behaved and very shrubby/pretty, doesn't spread like Gulfstream.

Red fountain grass should be cut to the ground once a year in late winter as new growth appears, to keep it looking good, not sheared into a bottle brush shape. It's a grass and needs to be refreshed. So you temporarily lose your hedge every year for a month or two. Is that going to work?

What about common myrtle, which shears into a really pretty hedge and can be kept at about any size. Its slow growing so one shear a year is fine, and can live on winter rain alone, provided we get some winter rain. The foliage has a beautiful sweet fragrance and the foliage is a deep, dark green year round. It's also very tough and long-lived. Boxwood does pretty good considering you are so near the coast. Inland it looks poorly in heat and in winter cold. These would be examples of standard easily available plants for reliable performance, rather than a trendy solution. Avoid Euonymous because it needs more water to look good and protection from scale and spider mites. It looks great in a pot at the nursery but commonly not too good in your yard a couple of years later.

Jade plant believe it or not makes a decent hedge and needs little water, but I'm not a jade plant fan myself.

I just saw common myrtle at the Water Conservation Garden here - it looks lovely. I was a bit taken aback that it grows to 10+ feet tall but it sounds like with the slow growth rate that is manageable. I'm going to keep researching that one - thank you!

Podacarpus? We had oleander at our other house, and it is easy to keep sheared low. We were on a golf course, and to view golf, nothing can grow too high.

If you haven't decided yet, check out the Manzanitas, there's a variety of them that are perfect for your area and fulfills your needs. You can try Greensphere Manzanita, Ian Bush Manzanita, or any other lower-growing manzanitas. They're all wonderful for hedges and drought-tolerant to the extreme! Look in the link below to see a list of manzanitas.

Here is a link that might be useful: Numerous Manzanita species (it's only a fraction of the total genus)

Good suggestion on the manzanita. It sounds like Ian Bush would be a good option since it also happens to be fast growing. Do you have any experience with Sunset Manzanita? I like the look of it and my local native nursery has it in stock. I will have to ask about growth rate.

Sorry to say, but I don't have any experience with Sunset Manzanita; while I've never planted it before, I've heard many great things about it, particularly the foliage color when it begins its winter growth phase. It spreads out pretty widely though, and primarily is used as a taller groundcover in most cases that I've seen. Nonetheless, I don't see why it can't be used as a hedge, especially in your setting. It also is relatively garden tolerant compared to the 'hardcore' manzanitas.

Just a recommendation: read up on the procedures for planting native plants, because it's a little bit different from the procedures of planting non-natives. If you're having trouble finding any manzanitas--or native plants for that matter--I recommend looking at Theodore Payne Nursery (if you're closer to Sun Valley) or the Escondido branch of Las Pilitas Nursery (if you're closer to Escondido).

Here is a link that might be useful: Theodore Payne Nursery