Ask maps
Put in your address and then the address of the park in which you are interested. It will give you exact mileage. The route may be wonky, but it will tell you if its driveable.
Texas RV website - I have lots of maps and resources.
Trails.com - find all trails by activity
Wildlife Trails - western east Texas is close to Dallas
Freshwater Lakes - Prairie Lakes region
Lake Lavon, Lake Ray Hubbard, Lake Grapevine and White Rock Lake are close to Dallas.
Network with other photographers in Dallas.