Hi Mark, the rules are quite simple. Your boat is over 750kg (940kg), so you need a braked trailer. The towing vehicle has to have a towing capacity, which exceeds the gross weight of the trailer and the boat. For instance if your trailer weighs 500kg and the boat 1000kg, the towing capacity of the car/van must be 1500kg with a braked trailer. A Land Rover is a hybrid, so has slightly different rules and you need to check your tow vehicle towing capacity, because few can tow 2 tonnes now. For instance a 2 tonnes transit cannot tow a 2 tonnes trailer.
Now to the bounce or no bounce. If the trailer capacity is 2 tonnes (or 2000kg approx.), then it will be a little harsh, especially with an outboard on the back, yours is a jet, so that is less of a problem. What it does allow is that you can put a large amount of goods in the boat, including fuel and you could be nearer to 1250kg in your case, so it is still a little harsh, but on the safe side and less bounce at that weight.
What you could do is to replace the second axle (un-braked axle) with a 500 or 750 kg system and reduce its capacity to 1500kg, that will take the stiffness out of the suspension, which is what many trucks do with the smaller wheels behind the normal wheels. You would obviously have to stick with normal wheels, preferably the ones it has now.
As an example, a Suzuki Jimny has a total towing capacity of 1300kg braked, but it can only tow a 350kg un-braked trailer. It cannot tow a 750kg un-braked trailer.
The good old Land Rover can tow 3500kg braked, but the LR does not weigh 3.5 tonnes, there is more, but hope that answers your question?