All of my avocados are in the ground. I use mounding methods and some bricked raised beds. I do amend the soil to make it drain faster that I use on the mounded and raised beds.
Have used Florida pits with 100% success, or in the case of one I didn't like, Brogdon, multi grafted to a bunch of shoots that came up from the Waldin root stock after I stumped it.
Corpus Christi has the same black gumbo Victoria Clay Series that Houston has. Here's a young, bearing Don Gilloughy avocado tree in 2 rows of concrete tree rings in 2004. Partially shaded too.