Just my two cents but two things I would not do.
1) Buy a used vehicle in New Orleans right now.
2) Buy a boat on ebay.
Your concerns are valid so I would go to a dealer. If you buy off Ebay there will be very little recourse.
I own a 2004 170 Bass with the Yamaha F75. I really didn't worry about the weight issue as I myself am not a thin man. If I want to get 50 pounds of weight out of my boat I'll diet.
Finally I bought the 170 Bass for fish ablity For my fishing habits its perfect plus fuel prices aren't going down.