Chris,
The design is very simple - one of the requirements being that it can be fitted and removed in less than a minute. Another requirement was that it should not occupy valuable van space when not in use.
It is constructed of a 6' x 4' plastic tarpaulin and has a single transverse aluminium pole that fits across the top of the back doors at the rear end and has a vertical drop section of about 6".
The front end secures to a gutter clip on one side and on the other a bungee between the tarpaulin and one of the vans' rear wheels, maintains front tension.
Rear anchoring is by elasticated straps that form an "Lazy Y" which both holds the transverse bar down and the vertical rear skirt tensioned to prevent foreword movement. The rear doors of the van, left open form the sides of the enclosure.
When not on use, it is rolled up and lies on the high rack alongside the hand pile brush and other long items.
A more elaborate awning would be easy to design and build, but I wanted something that would attach to the van alone - and I had no wish to stand in the rain for more than a few seconds when taking it down. The van can even be moved with awning attached, simply by transferring the wheel fitments to the wheel arch.
For more complete cover a rear drop-sheet can be clipped on, but this requires heavy anchor-weights for the lower attachment, and I would not trust it to stay in place in gale force winds - as the main canopy does.
John.