I agree that box squats are a really great lift. Don’t believe me? Go over to the westside barbell site, or their videos on youtube. They almost always train with boxes and those guys move some serious weight.
You said you were a tall football player-- like me. I have the exact same lower back issues, which i was always told it was just a hamstring tightness problem. My advice to you, stretch those hamstrings and squat on a box!
Dont just touch and go on the box, Sit completely down on the box and use a wide stance. Check out westside barbell, and they’ll teach you how to do them.