I would not bother: too expensive. You can get a good 6x4 garden trailer for $300-400 and build a body to drop on top, exactly how YOU want it, for about $200. I made one for $100 when I kew peopel in the trade and could get the steel sheeting to cover it for next to nothing.

hello Mineral,
i agree with Mark to some degree- find an existing licensed trailer and convert from there, although you would want at least an 8x4 trailer to have any hope of squeezing gear into it. i have recently gone down the path of converting an old trailer, (8x4 +2' of space on the draw bar)and its the best thing i have ever done in terms of keeping gear organised and together and able to move as soon as the trees start to rustle
esentially i built a steel framed ali clad box that sits on top and is hinged on one side and the other side has a key lock arrangement. if you are interested i can send you some pics. good luck

Comrade Mineral,

A mate of mine has custom built windsurfing trailer in Perth
It has been parked up for 12 months so not sure about rego but know that he would be keen to move as he has been posted interstate

It is fully covered all the way along the draw bar so you can get heaps in it and it makes it a little more aerodynamic for towing

Let me know if you are interested an I will chase up a location and price so you can do a drive by and take a look

Kremlin