DC 4 airplane engineering question

the wheelbase is very short relative to the fuselage https://en.wikipedia.org/wiki/Douglas_DC-4#/media/File:Pacific_Western_Airlines_DC-4.jpg

the 4 engines weigh a combined 7,000 pounds..it would seem like even with the weight of the engines, it's not enough to prevent the plane from tipping backwards. If a really fat passenger sat in the back of the pane, it would tip