In a coup that small I would put the nest boxes out the side of a wall. You don't have much floor space and you may also care to have food and water inside for them which will also take up floor space. I'd suggest getting a feeder that hangs on the wall to save on floor space too.
One other suggestion, go bigger! My first coup was 4'x4'. It was used for 2 or 3 months and before fall I had built another one, because 4x4 was just too small and I already knew I wanted more chickens.
One other suggestion, go bigger! My first coup was 4'x4'. It was used for 2 or 3 months and before fall I had built another one, because 4x4 was just too small and I already knew I wanted more chickens.