Can you post a screenshot with the bounding box visible, before and after the correction?

Hm, I'm a bit irritated. I thought Bret's code carries the model's box _above_ the ground, but this doesn't:
"if(ground_dist > 0)"

I don't use the code, so I'm just guessing:

ground_dist IMO must be higher the zero, about 20 or so, depending on the models size and the slopes etc.. If it is zero the collision box always touches the ground, but you should avoid that.