I am finishing up my coop for 2 SLW pullets and two Polish pullets. It is going to be @ 6' X 4'. Because of where is is situated I really won't have access to the left wall and back wall from the outside. So far I have one nest box that measures @ 22"w x 12"d x 14"h. I thought I would just split that in half to make two boxes that they would share. Do I really need 4 nest boxes since the Polish are not particularly steady layers? Can I get away with just the two? If necessary can I make more of an over/under design or do all the nest boxes need to be at the same level?