I have a buddy fixing to buy a New 34 Sea Ray and he thinks he can pull it with his Avalanche

. I figure that boat weigh's around 16-18k pounds

. This aught to be a good one to watch.I am bringing my camera

. He is moving up from a jet ski and had a ski boat once so this will be his first real boat.
I told him he needed a Dually at least and that might not be enough truck. He asked could he put a dually rear end and fenders under his truck to help pull it.
What do you think is going to happen ??
Rob