Antony, to me, the significant characteristic of the design of this trailer is the intention to lower the height of the bed as far as possible. Are there sixteen wheels ? I can only see eight relatively light duty, fairly small diameter wheels. Certainly, placing the axle above the leaf springs suggests the need to lower the bed was more important than carrying a very heavy payload.
I'm surprised the unusually low ground clearance of this trailer didn't cause it to constantly bog down while it was on farm duties.
Possibly, the key to figuring out what this trailer was built for is to understand why it needed to be so low. Was it's load very high, was it intended to pass under some fixed structure or is it simply a low loader used with rear ramps as it was during it's farm days ???????
What kind of braking system does this trailer have and are there any indications that it was designed for road use or intended to be confined to an airfield, dockyard or works ?