I used 3/4" EMT for a teardrop shape frame for a canvas cover. T joints and X joints were made from short lengths of welded 1" EMT; standard 3/4" EMT couplings used for linear joints. I later replaced the canvas cover with FRP (fiberglass reinforced plastic) attached directly to the EMT with 3/16" pop rivets. Held up well.
The large radii were hand bent on a jig made of wood blocks attached to OSB; the tight radii bends with a standard EMT bender.
The entire framework was hinged at the front of the trailer to form a clamshell to allow loading a dual sport motorcycle in the trailer bed.