After the DTE on my truck gets to 15 or 16 km it will change to FUEL LOW. I can go up to 50 km before running out, which I have done once. I have on a couple of occasions put 96 litres in my 98 litre tank after driving to the fuel station. All of this not towing. I don't make a habit of running ultra low but in 5 years of ownership circumstances get you.
As to the comment of the dirt and stuff in the bottom of the tank, well the fuel pick up doesn't move when the tank is full, it's always sucking from the bottom. That's why they filter the fuel.