*My trailer from the 1980s is essentially what Harbor Freight sells today.
*They go on sale regularly so you might get a price break there.
*I made a plywood flatbed,then created a top.
*The top is 1/2-" EMT,bent with an EMT bender and gas welded into a space frame,covered with 1/8" Lauan plywood/fiberglass,and cast fiberglass radii,laid up inside split PVC pipe 'molds.'
*The wheels were 13" from a CRX,reversed.(I had to grind the wheel centers to fit over the hubs.
*All-Season radials from Discount tire were okay for my light loads (1/4-ton max)
*As pulled,with no belly or gap-fillers I lost 2-mpg @ 55-mph (50-mpg) Denton-to-Los Angeles round trip.
*If you're spooked by the Chinese wheel bearings,you could pop in Timken or another brand.Just set enough 'slop' in the preload and use nothing but wheel bearing grease.
This is a study I did for your car.It is excessively long, enough for camping.As with BamZipPow's 1-wheeler,the idea was to get the streamlining good enough that you'd 'gain' mpg while pulling it.
Another:
This profile would be okay for plan taper
