Just "rig" any 12-volt appliance with the hitch connector and you should be good to go. Current draw would be my main concern on wires that light. Now, if there are two 12-volt lines coming of the connector then you may be in good shape. If I had a spare battery, connector and the 12-volt appliances I'd give it a whirl.
NOTE TO BLAST: On the concrete driveway with ample fire suppression stuff around...
Check out
http://www.roadtrucker.com for 12-volt apppliances. Standard Disclaimer