You guys in So Cal, there are some real good stone fruits that don't ned high chill hours, and even the "Dave Wilson" varieties that say they need high around 300-500 can fruit where I have my sensitive plants. Take Blenheim or Royal apricot, they are supposed to only fruit at 400 hours, but I can get plenty each summer, and we're lucky to get 100 actual chill hours each year. Even my friends in the warmest parts of Vista have fruited Pawpaw, Pluerry, Stella cherry and some real good apples, pears, and stone fruit crosses. I just ordered the "Nadie" a true cherry plum cross unlike Pluerry.
In order to save space I have 4 rootstocks planted 18-24 inches apart and have grafted about 30 stone fruit varieties. I'm just going to experiment with chill hours and some force bloom methods to see what comes out.
I also grafted a bunch of Asian pears and different apples. My high chill apple varieties do fine here such as Granny Smith (400 hours), Beverly Hills (300 hours) Mutsu (500 hours) Pink lady, Fuji (500 hours).
I have 3 varities of Pawpaw in the ground, all planted in the same hole, they have flowered, but no fruit have set yet.