Man, I45 is a BBQ desert. Woody's smokehouse is the only spot I can recommend. Above all, avoid Bubba's. Take 287 to 45 and you add the newer tourist stop just the other side of Midlothian, near SWFA for a bonus. Their BBQ is passable. Good sides.
Seriously, I will haul 407 BBQ down there and I usually go every two weeks.