I didn't quite realize what the intended goal was when I answered your post on GON. I thought you just wanted a new boat, not needed one to be lighter. #-o
Anyway, was your old Tracker one of the older riveted ones? I'm not really sure that you can get too much lighter than that, as they (hulls at least) were fairly light. Now, if you have waterlogged plywood in it, that will certainly account for a good bit of weight.
Finding a boat without plywood underneath the bow deck is going to be tough. Most companies have it, G3 does, Alumacraft does, etc. Also, not having the plywood isn't going to gain you that much in weight savings. Sure, some weight can be shaved here and there, especially if that is the main concern when designing the layout, but it isn't drastic, especially when you consider the heavy things are the trailer, batteries, trolling motors, etc. Most of my customers go with aluminum for the longevity more than anything.
If you really wanted to cut weight, things like swapping out a steel trailer for an aluminum one would be somewhere that an advantage would be seen, but at a cost. Eliminating a battery is good for another 60 pounds or so, but that might be prohibitive when fishing (aren't you a guide?). From a practical standpoint, unless you are dealing with waterlogged plywood and saturated flotation foam, I'm not seeing many ways to cut any significant weight.
What are you towing with?