Deano, you'll raise a smile over this (given our 'market garden' commonality in the distant past)....I've built a couple of trailers in my time.
The first was for towing behind the Fergy and was for knocking almonds. It was all steel, 22 feet long, four feet wide and eighteen inches high. I was pretty handy with a welder when I was 16.
Second was a little smaller, and its claim to fame was my own version of knee suspension. Remember that concept? Independent suspension using a large single wishbone on each side?
Cheers,
Glen