From all the pics I've seen from various angles there doesn't appear to be any attachment points at the bottom...maybe a small bracket slips in the wheel-well where the fender flare splits from the corner bumper piece; but I don't know about around back by the hatch. It sets out so far from the body of the truck that we should see some sort of bracket or something...
Perhaps that's one of the reasons that it caused so much damage when it took the impact...if the bottom didn't have proper support it would just bend right in. Perhaps he designed it as more of a ladder and less of a guard/ladder.
EDIT: I take that back...I think the rear bracket can be seen in this pic. If that's it I think it's a little weak. I'd liked to see something beefier than that; and maybe another in the middle.
