the swim platform has a nick in the trailing edge, looks like they smacked something.
that's pretty cool that you can see the stringers and muffler in your sunsport mikey. z51, if the boat you're looking at is like that you can't lose on that fix. some of them have all of the hardware under the floor though, like mine.
i see what leaf is looking at, why is there unfiberglassed wood under the floor? some of it looks like wet dark wood...saturated maybe.
the gash is ugly. there's alot of fiberglass in that part of the hull but if you do have a leak...i'd run. you've got wet foam which means that someday the unfiberglassed wood will rot.
if this guy won't come down a couple of grand on the price, i think he's making the decision for you. poke a finger or screwdriver up that gash (can i say that on here? ha!) and see if you've got solid glass or foam. also see if you can see the stringers and platform bolts like in the picture mikey posted.