ok, thanks, everyone. I was going with 5'x5' because it was wider which gives them more space to hop onto roost and apart from nestbox rail but did forget to keep measurements in terms of 4s and 8s (like we did with the run). We will rethink the dimensions of the henhouse.
(even in winter we do shovel their pen so they almost always come out for a bit even in foul weather...but 7 will be a new high # for us so we want to keep things as peaceful as possible, especially with the age differences).
Back to the drawing board!