OK I figured out a way to weigh my boat using a tongue weight scale, any of the scales here are hard to find/too far etc. I got a surprise, similar to what you found, the dry weight for this boat is listed at 2560 so you'd thing wet weight with equipment, roughly 3000 lbs and the single axle trailer should weigh about 800 lbs, for a combined weight of 3800 lbs. Well, I got 5040 lbs boat on the trailer with 1/4 tank of gas. And, I redid the deck/stringers on this boat 15 years ago, it wasn't waterlogged then and I'm sure its not now.
As I said a number of posts back, for the original trailer for this boat, the carrying capacity of the trailer was 3750 lbs. So even though "dry" weight was listed at 2560, they must know their weights were way off.
When people talk about boats being waterlogged, its not that it can't happen, it does but think about the required volume that 100 gallons takes up. The only way I could see that is on a boat where there is no foam, and under decks was all full of water. On a foam filled below the deck boat it just does not make sense. 100 gallons of water is about 800 lbs. The volume of that is about 13 cubic feet. Where the heck can you fit that much water on a foam filled boat that is 26' long? Not to say there is none, but the #s to me do not add up. I think it is a case of the boat builders not providing accurate information.