Yes that would be most helpful but I dont have autocad. My van is a Bailey Indiana and I have a mover so i dont need that much free space, no more than 12 inches each side. Thought I would need about 8 x 1 inch x 1 inch steel legs with bolt down flanges. my only concern is the wind blowing the roof off!
I would go with 5x5 timbers in the corners with a 3x2 roof frame. Sink the uprights into the ground via concrete and glue and coach bolt the roof frame in place. It would take a major wind to damage it then.
Using polycarb sheets for the roof is light and strong. easy to get from wicks and easy to clean with a brush.
Make sure that you put the uprights out of the way of anything you need to open on the van and round the edges off so you can walk past with ease. Use planed timber so you don't get splinters rubbing past them.
Good luck with it, if you need help with the design. let me know
Steve