I suspect you may have other replies to your request, but if not my wife and are RE investors. She is a licensed realtor, and I am the investor side. So, she would definitely be a friendly REI agent. We are new on investment side, 2 SFR rentals, and like you prefer newer built rentals. I focus in Ellis County for investments so would not compete with your locations, it sounds. We get in to the very south side of Dallas county also.
Let me know if she or I can help in any way.
Mark and Julie