Good job on the trailer.
I thought that I had a pic of Steve Delaire's aero trailer. His was 2D shaped much like this car.
Teardrop shaped when viewed from above. I recall that it was about the same height and max width as his vehicle.
He used it to haul his bicycle streamliner. Told me that it improved his fuel mileage 3mpg when towing with his van.
He shaped the main structure (1" square tubing) by screwing appropriate wood blocks onto the deck behind his home. Then he pulled the tubing around the blocks making 4 equally curved shapes and spaced them with straight sections. The door was on one trailing panel. That had a piano hinge with the clasp at the point at the back.