Nice looking and spacious greenhouse, Brandon. Being in Texas means your greenhouse is going to cook!
You could consider the following:
Install an exhaust fan on one side (high) with an intake on the other (low). You want to size the exhaust fan to be able to change the air in the greenhouse in 1 1/2 minutes. Fan capacity is rated in Cubic Feet per Minute or CFM. Here is a guide you will find helpful:
http://www.charleysgreenhouse....
Aluminet shade cloth will also help to control the heat and intense sun:
https://www.aluminetshadecloth...
Evaporative cooling equipment can be of help, but it is expensive. For a hobby greenhouse such as yours, you could look into a fogger or humidifier. Both foggers and humidifiers emit water droplets so small that the plants within the greenhouse will not get wet. Instead, the water quickly evaporates and helps to cool the greenhouse. You would want to use one in conjunction with fans to circulate the air around the greenhouse. A very cheap way to do this is to spray down the floor several times on hot days.
The above links are for your information. You should shop around for the best prices, but these would get you off to a good start in controlling the heat in your greenhouse.
