Make drain pipes out of brass and just energize the pipes. if the structure is wood, it'll insulate 2 of them from each other. Run the hot up one side of the building and the neutral up the other. Solder feeders to the bottom and get the bottom of the pipe close enough to the table to hide it in static grass. Inside the building, just wire up the LED by soldering them to the top of the brass wire. If you step it down under the table, you're talking about a few volts DC though the exposed wires.
Alternatively, pile junk on the deck underneath it so you can hide the wiring in a stack of junk.
