My trailer is nearly done, it replaces my VW T5 which costs more than a Porsche to run.
The front half is rolling workshop, the rear half is for bulky goods, or sand, mulch etc. It will be getting a roof rack for long loads, alternatively 4x8 sheets can be strapped to the bulkhead.
I can't think of many jobs that this trailer won't work for and my small van + trailer is more flexible than just having a big van.
Not much attention has been payed to Eco/Aero as I really needed to get it done asap, I plan on chopping and changing it until I get it exactly how I want it, then I plan on doing a MkII with the lessons learned.
It looks bigger than it is in the photo, the total floor area is only 7x5'. Internal height is 5', I plan on adding a dropped floor so standing inside is possible. For now the high matches the tow vehicle.