Metal billboards!!! Use 5 (or more) billboards and trap the dang golem in one spot. Make sure you get one on each side AND through the golem.

You can set up a cannon defense wall a little ways away. 3x1 foundations across and the cannon is in the middle. Place a metal single door frame in front of the cannon and then solid walls on either side and one level higher. Good defense! Aim and shoot!