Well, I have a mate with a late 2300 with a 300 yamaha, and it is legal behind his cruiser, but north of 3 tonne. And the bare hull weight on those is quoted as 1500kg
This "bare hull weight" business can be very misleading, there is no standard to compare it to. For example, my Reefrunner is quoted as 1050kg dry hull weight. With a 150 Merc 4 stroke, a bit of fishing gear ( no eskies full of ice, for example), and the 220 l tank half full, it weighs 2550 kg on the weighbridge. So I can't see a boat which is meant to weigh another half tonne more coming in under 3 tonne, particularly with a heavier motor and bigger fuel tank.
I've seen people tie themselves into knots over this, when they add up the supposed " bare hull weight" supplied by the manufacturer, the (dry) weight of the motor, quoted weight of trailer, chuck in a bit for batteries, then wonder why it weighs a half tonne more than it " should" . Everything weighs something, and it adds up.