It sounds very heavy to me.
I have towed similar amounts with a diesel series landrover and with my disco, however I was going very carefully and leaving miles for braking. The LR manual, at least for the disco, states that you will need some sort of coupled brakes (ie not overrun brakes) for loads of that magnitude.
I would say that if you are getting a load of sand or similar, and it is an occassional thing, then do it, but in your case you are planning on dragging this trailer around on a frequent basis and I suggest you would be better served by one of the massive diesel pickups that are so popular in your neck of the woods.
Regards Stephen
PS: best would be to try and tow the th