Now had it been me, I would have wired 110 to the sign and installed a small light to illuminate it at night.
Funny thing is, I don't do to well at wiring projects so the possibility a open circuit could happen is high, and by grabbing the sign one could become the actual circuit to ground. Lawns at night tend to draw condensation which allows for a great electrical connection. :)
A Parmak battery operated high voltage fencer costs $35 and puts out 5000volts in pulses. The poly tape costs $15 for a 1000' roll and hot glue costs a few pennies. DC current at high voltage but low amperage can knock you out or leave you unable to move your arm for an hour. I once backed into my livestock fence on a hot day without my shirt on and the wire touched me at the back of my neck. Threw me fifteen feet and all I saw was a white flash. On a normal day when touched by hand, it will just feel like someone hit your arm with a sledgehammer.
Isn't that the purpose of the exercise?