The cover garment can be a challenge, especially in Warm Weather. I am in the same general area as you. I am Club President at the Big Piney Sportsman's Club near Houston Missouri.
We had a match on 2 February. I wore a Deluth long sleeve Henley tucked in with a tee shirt under it, and a large over shirt as a cover garment.
In warm weather:
A vest is not a bad plan.
Short sleeve shirt unbuttoned will work. Nylon Fishing shirts are not a bad choice.
A Larry the Cable Guy Shirt constructed from a BDU Shirt sounds like it would have some potential for an econo cover garment.
As was mentioned above the vest will sweep back out of the road helping your presentation. You can even have the vest starched to help it sweep out of the road.
I ran across a source once for a lady who custom makes an IDPA Compliant Vest. Seemed like the price was not terrible. Selection of colors, etc.
UP DATE: I just looked this up. Becky Sells, located in Conroe Texas
Home Page
Becky custom makes the vest to fit you. Rip Stop with a Mesh Back Panel is an option for warm weather. Custom Embrodery Work Optional. Lots of colors.
I have an old OD Green vest I have had for 20 years. It is plenty long enough to cover my 64 or 686. I like my vest to be plenty long.
I do wear my vest some out in public, along with my old Booney Hat. I am an Old Guy, and invisible.
I need to get up to the Cup this year. I keep planning to make the trip, and first thing I know it was over last week.
I shot on your range around 1976 or 1977. I was shooting IPSC back then. I had a Wilson Combat 1911 when Wilson Combat was the empty store beside his dad's Jewelery Store on the Square best as I remember.
It would be nice to be that young again.
Bob