You have a beautiful yard to work with--nice big shaddy trees, grass etc. Simple blocks or cinder blocks would be work. Here's something I just had put up (I have a few dogs to keep out of this enclosure)...we had to cement the post into the ground, I lined the inside bottom with blocks..but decided to use this lattice so I can grow vines up along the side.
I'll take more pics later tonight but have since added 2 patio umbrellas for shade, a dog igloo that they both go in to escape the heat and at night, and 2-3 water dishes throughout. I'm adding more and more every day and just planted a few hibiscus in pots so they can eat the fallen leaves and flowers..and roses.
I live in AZ and the temp last week of 117 and I was able to maintain 95-104 under the shade and in the dog house buy using both patio umbrellas and by turning on the sprinkler for just a min 2 times a day. I'll take more pics tonight.

http://i87.photobucket.com/albums/k132/dawgcr/tort.jpg