Hello all.....I have a question about the next boxes that are stacked on top of each other. How do the chickens get to the top boxes if the perch in front of the boxes are the same length? Should I make the bottom perch stick out farther so that it would be easier to get to the top ones, or will that be too tempting to roost on? Some help and guidance would be appreciated. Oh, and by the way, I was planning on putting them 18" off the ground. So the bottom two will be 18" off the ground and the top two stacked directly on top of them.