Mate of mine made one, using 1" tube, brackets fixed to the side of his van, and some assorted brackets to give the right angles, and a Mig Welder. The actual awning he had made, with eyelets around the edge, and rubber bunggy straps.
Takes about 5 minutes to erect, and dis-erect.
He uses it as a cover/ pit area for a dragster when he goes racing.
Andy