Wish I would of taken pic. Saw a pretty stealthy looking van couple months ago at local bog box store. Got talking with the guy who was really into that type of thing. Anyways his license plate folded down with some type of hinge, behind the lic plate was elec hook up connection. Don't know if that makes sense to you so included link to what I think I saw. Many car in the 60's had fold down lic plates with gas cap behind them. His lic plate had elec hook up behind his which looked really good.
http://www.truckspring.com/towing/trailer-hitch-accessories/fold-down-license-plate-holder--49802.aspx http://dodgeram.info/tech/mods/bumper_step/http://www.etrailer.com/Hitch-Accessories/Hidden-Hitch/8802.html