How many miles per year do you plan to pull the trailer, and at what speed?
The lower your walls, the better the aero efficiency, and you'll want to cover the top. When my 2ft walls are up, but nothing is in the trailer, it's like a parachute is attached to the car. When it's full, it hardly affects mileage at all.
What are the mixed reviews about the Harbor Freight trailer? Mine has been great, and folding it make storing a breeze. My complaints are that it uses a 1 7/8 ball, which is much less common than 2", the wiring for the lights are garbage and should just be thrown away instead of installed, and it takes forever to assemble (there's about 90 bolts) plus building the deck and sides.
Here's my trailer album:
https://ecomodder.com/forum/member-r...s-trailer.html