They will offer a stupid sum of money for volunteers to get you in a compliant seat or you should take the next flight with a compliant seat. My experience was EWR - YYZ on an oversold 50 seater and the offer was enough for both of the two crew members to buy a 5 yr old Honda Civic and drive canonball run style. The next flight was also oversold. A limo one way was 2000.00, a rental car was $300, and they spent 5 times the limo buying two seats and created a whole heap of drama that does not look good in a crowded boarding area. The people managing these situations aren't good decision makers and they are afraid to think outside the box.