Everything I can find points to 2840kg payload.
www.cotswoldtrailers.co.uk
Only the short skid option has that payload, the long ramps is probably 10kg if that lighter, no idea on the short or long ramps version they just tend to put the headline figure and no more.
Unless it's changed indespension alumax is has the highest payload of 2.91t
Woodford trailers are developing one, I've not seen it in person but a mate has it as a trial/demo looks like it could be ok but needs quite a few tweaks and unsure on weights.
I've got a MK1 Brian James cargo tipper, at the time was the lowest bed height of all tippers by something like nearly 70mm. It's a few years old now and rattles like a twat, going to give it some love at some point and swap some stand springs update the rubbers where the bed sits on. It's either the rear jack legs that rattle (to be fair they are utter useless) or the ramps which again are made well just poorly implemented on how they store, you have to flip them over and put them in backwards. Not sure what genius thought that was a good idea Vs just dragging them out of the holder and hooking on to the trailer, sides were crap and were replaced with redesigned version (original ones had pretty much a 10mm gap down the sides which was apparently satisfactory

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To be fair it's still on the original plank bed which is metal coated timber through the middle 2/3