To anyone wondering: This guide still works for defending in the reworked Barbarian Assault. It'll look very different but if you just look for the same general markings around the floor of the map you should be good to go. The spikes were replaced with swords etc :)
Since we play Oldschool BA as well, it's easier for us just to stick to clicking the food. Also no new guide since the nerf because it'll be patched soon. If you ask around you might find a method though.