Here are a couple of pictures of the spot.
Thanks for the responses!
That larger tree is what we're talking about getting rid of. If we took that out the space could be up 6x15. (18 square feet per hen) Now that I think about it if we cut the tree back it'd probably make the area a little cooler, but because of the position in the yard the tree would never cast a shadow over the coop, though the bushes to the left of it will. And we could easily use the tree to hang a sun sail.
I would assume we're a bit cooler than Fallbrook. But I don't want to stress them out when those winds kick up in the late summer either.
Also a good consideration about the critters, thanks for mentioning that. We've got 2 dogs and a cat... I'm primarily thinking about keeping them out. My office is actually in the backyard and I've not seen rats or raccoons. But we definitely have the occasional opossum.
Seeing the photos, anything else I should be thinking about? We're planning to have the coop towards the inside of the yard as opposed to up against that wall so that it's far enough away from the property line. But it's fine to have the run go up to the wall, I presume.
All your ideas are good ideas if they work for you. Whatever you build have good run-off away from the pen area for those occasional gully-washer rains we get in SoCal. I set my first small coop up on a paver stone foundation and it helped keep the pen area dry. You should think of good cover not from sun so much as those gully-washer sudden downpours we get. We had a pop-up canopy over our first little coop which also kept us dry when we collected eggs. With our larger Barn Coop we're building a patio roof over the coop which serves as protection from sun or rain. I don't care how well-built coops are they eventually warp, peel, or leak so after 5 years of struggling without a formal cover we've finally invested in a patio roof over the new coop.