Love the pond area! I also had a blank slate at this house. Everything was so overgrown with fig ivy when we moved in a bit over three years ago. The ivy was strangling the oak tree and had already killed everything else in sight. We pulled 99% of it out, but left some on the wall behind the air conditioners to keep the green effect there. What was left resembled what you have there to start with. You'll be surprised how quickly your garden will look mature in our climate. BTW, you and I have identical climates, Don. My lifelong best friend lives in Baytown, and usually I get her weather one day later. Her garden has many plants that were started here and took the roadtrip west to her house. The latest new arrival at her house was a Lecompte vitex tree that relocated from here to there last summer.
What kind of tree is over your pond? We have a tree over ours too... hate it when the leaves drop, but love it the rest of the year.