You could get a roll of 12/2 G or 10/2 G UF copper cable and run that. Better conductance than extension cords.
There are problems with that arrangement. It would deny the opportunity to put up and put down cords every time I mow. It would make fencing less vulnerable to overloading outlet during storms. It would be smart. Some things simply are not to be on my little farm.
Jim, That type of conductor (UF) is made for permanent direct burial, so no mowing issues there.
