Suspension

Short answer is NO ,if you want to upgrade to 3 T you will need a 50mm axles ,10" electric brakes 195x14 LT tyres ,and recertification from a registered trailer examiner ,with new compliance plate .If you are rated at 2 tonne ,the chassis may need to be upgraded as well to get 3 T

Axles is plural, so I presume you have a BIG van, ie 2 axles.
If each axle is 2 tonne, as stated, then the rating must be nearing 4 tonne for the van which is more than 3 tonne.

Why not check with the caravan manufacturer. If they are uncooperative then try the chassis manufacturer.

Lets start at the very beginning, because it's a very nice place to start.

A/ so we have a dual axle trailer with 4 wheels.

B/ exactly what axles, hubs and wheels do you have?

Is it 2 tonnes combined or 2 tonnes each axle?

What is the current plated GVM of the trailer?

C/ What are you actually trying to achieve?

If you are trying to recompliance with a higher GVM ..... that could be more expensive and complicated than you may be prepared for.

IF you are simply looking for a stronger suspension with the same GVM, that is another story.

You can do 1.5 tonnes per axle on ford bearings.

IF you have 45 or 50mm axles and you are running Ford bearings you may already have 1.5 tonne axles.
AND those load capacities can be achieved on 14 inch light truck tyres

Remember this is bearings ..... not stud pattern.

Now if you want 3 tonnes per axle ...... yeh well the game now gets far more expensive, particularly if you want a 6 tonne GVM.
You will be on 6 stud rims and 15 or 16 inch tyres.
AND
That takes you out of the light trailer catagory and you will be towing with a truck on a truck license.

If you have 2 tonne axles, they will be at least 50mm and you will be running landcruser or some other 2 tonne specific bearing
.
Most commonly you will be running 15 or 16 inch tyres, though there are some specifically made 6 stud wheels that take 14 inch tyres and if you are very specific about the tyres you can run 2 tonnes on 14 inch light truck tyres (just)

SO
Back to the ABC and the doug ray me
cheers