Growing salad greens when summers are too hot for long

Lettuce grows beautifully here in the cooler months and turns bitter or bolts as soon as the real heat arrives. I'm thinking of accepting that as a seasonal crop instead of fighting the weather, then using shade cloth and heat-tolerant greens for summer salads. Has anyone had good results with succession sowing in partial shade, or does it just delay bolting by a few days? I'd rather harvest smaller leaves reliably than chase enormous heads.