I know a lot of the dirt roads west of I35. Nothing I'd consider technical or trail like (unless the James River Crossing is considered "technical"). I know most of them near Ft. Hood. Just fun...... and pretty country to ride through. Too easy for ya? Speed up. Things can get pretty damn interesting at 100. lol
I use Roads of Texas and the TXDOT online county road grids. Then I'm only wrong half the time.