Doing an event that is requiring running hot water for me to obtain a license. I have a 4 gallon electric mini-tank water heater with a 6 ft. power cord. The electric outlet is 20 ft away, How can I connect the heater to the outlet. Manufacturer does not suggest a extension cord but I have done research suggesting that as long as the amps and wattage of extension cord is the same or greater than water heater it can work. Any suggestions?