Think you can buy some little strips from the chemist which you place over the nose just before bed......no not to suffocate him......they are meant to hold the nasal passages open ensuring a better airflow so lessening the snoring. Or you could try sewing a ball or similar in the back of his jimjams or t-shirt so whenever he lies on his back, usual position for snoring to occur, it will be uncomfy and force him back on his side.