I would really recommend going with a 16' over a 13-15. The difference is pretty sizable and you really aren't going to gain much weight. I had a 16' starcraft that served very well for the needs you described and had plenty of room for 3 guys.
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When I grow up I want to be,
One of the harvesters of the sea.
I think before my days are done,
I want to be a fisherman.