motor shaft length vs transom?

[Pirate]

I know this is an old thread but I am faced with this problem. I have a 18' Trophy WA with a 25" transom. I got a great deal on a 2011 Suzuki DF140 sold to me as a 25". After bringing it to the Suzuki dealer to check hours and such I find out it is a 20" shaft. This motor still has 5 years of warranty left on it which is transferable to me. I don't know what to do, I guess I will sell it and keep looking for a 25" motor. I spoke to a few mechanics who said it could be done but there would be problems in rough water. Any suggestions would be greatly appreciated.