I'm a medium weight guy (165 lbs), but if there is one thing I noticed from some of the heavy hitters that they don't do, they don't get down.
You may be a big guy, but TUCK dammit and shove that ass back into the hump. (god that sounds really bad)
I see a lot of big guys just sort of lean down, but don't really tuck. Yes, there is room, get down!