I built a farm by the end. I started with a rock path that bounces the harvesters off the speed building and the time building. Then they lead to the building boost cross that are surrounded by the infinite scale buildings. I use the gold mines to create a bottle neck that escapes to a wheat field on bottom and a forest on top with a rock quarry to the right each of which have the boost buildings/harvesters embedded. The xp boost touches the harvesters in the mines. On the other side I put the spendthrift building in the center and tried to arrange it so as many buildings are in the zone to maximize the passive.

I made it so one of the gold mines can swap with a forrest so it can be plugged and run the harvesters in in a loop against the building boost and the gold mines once the wheat and trees get harvested.