[Brian Magee]

Jason
Have you considered this style of trailer?

Sorry about the quick sketch but I am sure you get the idea.
If it was made from light box tube and covered with thin ally it should be very light. If you use 14" wheels the door should open over the mudguards. You have no doors to make, just a hinge at the front. Asuming you load the car backwards you could reduce the height of the back to suit the car. Also you can make canvas sides to fill the gaps when the trailer is open to make a waterproof workplace. A slightly curved roof would add strength and stop drumming.

Brian.