Forget the 3 tonne towing capacity on the Rodeo. Any 4 cylinder diesel towing 3 tonnes is a joke. All the new dual cabs talk up their 3 tonne towing capacities but I wouldn't be towing anything over 2 tonnes any sort of distance in anything smaller than a cruiser or trol. Sure the newer CRD engines are good, but at the end of the day it's still a small engine pulling a big mass.
As others have said, towing your sort of weight will be a bit of a struggle for either vehicle, especially off-road. You'll really be flogging it to move that boat on sand. The fuel bill will be astronomical too.
I'd be more inclined getting a late model 80 series or early model 100 series Landcruiser. If you need it for work, get a trailer. I'm sure a patrol would do the job too but not sure what model you would be looking at for your $. Just steer clear of the 3 litre diesel Patrols. Very bad news.
Either that or get a smaller boat
matt