Hi Kevin, I have come across a growing system that I will use when I expand my container garden here in South TX.
The system was designed by Larry Hall and he calls it the self watering rain gutter grow system. I think this is the ticket to success but other's might not.
I think the amount of time and money put into making clay soil good enough to use would be better spent on the above system and you could be using it by the start of spring.
Check out Larry Hall on Youtube here
http://www.youtube.com/user/larrylhall
There is also Square Foot Gardening, starts with brand new mix and is in a 6" deep bed. this design is by Mel Bartholomew and is another way to go. I have containers and I now have two 4x4 beds using Mels Mix and they are doing great. If you compost all you need is your own compost to fill the hole when you remove a plant but start with mels mix in the beginning and I think it is foolproof.