There are two primary differences between the pre-2001 models and the 2001, 2002 models of the TV-18. First and foremost, the corner caps, which are separate pieces on the pre-2001 models, are brushed aluminum riveted to the transom and gunwales. On the '01 and '02 models, these corner caps are welded to the transom and the gunwales making for a solid corner connection. Andy, your idea about welding the corner caps down makes sense, since that's what Tracker decided to do beginning with the '01 model year. You may also want to think about drilling those loose rivets out and through-bolting the caps with stainless steel hardware, if you can.
Andy, do me a favor. Count the number of bolts/screws (not including big the motor mount bolts) that are through your and post it. I'll do the same on mine. My impression from seeing my boat sit side by side with a 2000 model is that my boat had more screws/bolts in the transom. That leads me to believe that there is some kind of reinforcing plate on the inside of the boat. That was the second big difference.
The other thing I noticed between the two boats (his had a 125 bolted on the back end), is that my transom looked THICKER. I can't prove it, unless I can figure out how to measure the thickness of the transom and have someone do the same to their 2000 or 1999 model. But I'm pretty good a gauging depth and distances and it just seemed to be the case.
Finally, I noticed that on the '01 and '02 models, the BOW cap is all-welded. On the pre-2001 models, it is a separate piece just like the stern corner caps.
One possible solution would be to look for a way to weld or bolt reinforcements in the areas which tend to pull apart (below).