So I have just been lucky enough to pick up a free trailer off a guy who lives around the corner. It's in pretty rough shape (pics to come after I can photograph it tomorrow) but I think if I strip the paint and rust back the chassis and frame will actually be in pretty good nick.
I'll have to do some upgrading of parts, like the hubs which have a massively spaced bolt pattern, and I'm hoping I can match the hubs to my KJ.
Currently the sides are what looks to be thin aluminium and everything including the guards and the doors looks to be pop riveted to the steel frame. The floor looks surprisingly corrosion free from the top side, but I'll have to flip it over to get a good look at the chassis and underside of the floor.
The plan is to use it as a trailer to tow our camping gear in (KJ's aren't great on space) and to use as a general purpose trailer at home.
Let's see how it goes.