Get you a used 15-20 in a 2 stroke johnson/evinrude, tohatsu or nissan. Watch the transom and if it flexes, then reinforce it.

I am always amazed by the folks screaming a transom won't hold up to a stump. Ok, point taken and agreed upon. So - you hit a stump at a blazing 8.5 mph. Now what? Oh yeah, stand up so you don't drown.