They sit on pillows on the floor instead of chairs. (nakedpastor.com)
We have never had problem with him falling out of it, we put pillows on the floor next to the mattress and we also had an area rug down. (ecochildsplay.com)
Put an extra pillow on the floor in case he falls out, or place the bed or cot mattress on the floor so it doesn't matter if he rolls off. (sleeplady.com)