On the ATR-72 [0] there is an extra leg that folds down at the back of the plane to stop it tipping over, and passengers at the front half must remain seated until the rear pax have left, so there must be some danger of unbalancing. These are weird planes in that the cargo is stored at the front, behind the pilots, and the only door is at the rear. They are prop planes, the 72 being a stretched 42, I believe.