I would transplant them to a shade location. I have three senior plants in the sun here in the SF Peninsula. One burns alot, one burns a little and one thrives with minor burning. I have burlap around the one that burns (not to pretty, but shades well). I formed a sort of box with redwood stakes and stapled the burlap around two sides and the top for shading. The other one that burns a bit will get burlap draped over the top. I use two four foot stakes and staple burlap (or shade cloth) between them. I'll drape it over the plant during the months that get a lot of sun.

Another alternative I used was to get a pot of bamboo that is tall enough to shade the camellia. I place it next to it and it helps somewhat. You'll need a boo that takes that heat. Maybe a bamboo clumper placed in the ground that shades the camellia.

Finally, I have a camellia sasanqua that is a wimp in any sun. During the sunny months I place a trellis in front of it that I covered in burlap. It works great and doesn't look bad at all. Good luck.

Actual camellia friend and grower in central valley can produce healthy camellia plant and better flower than that of coastal area of California.

If you can provide shade cloth overhead on wooden frame, your camellia will become a wonder plant to you. Well mulching, proper soil and timely water are important too.