aerohead's vehicle it wider than it is tall. My solution is for a vehicle taller than it is wide. It trades the second folding panel for a stinger that lies over the top.
If the vehicle is wider the stinger would be too, probably enough for the width of the license plate. Normally at the top rear, it would fold on a 4-bar linkage into a box that is open to the rear when deployed.
For the tail lights, I'd like '37 Chevy stalks with '59 Cadillac lenses. They could hinge out of the way to deploy the boattail and then swing back.
http://www.ebay.com/itm/Vtg-Antique-Chevy-Tail-Light-W-Stand-1934-1935-1936-34-35-36-Hot-Rat-Rod-SCTA-/171921245918