Pooing in nest boxes and lack of perching- any tips?

Of my five birds only one perches to sleep the rest snug up in a heap on the floor (mighty deep shavings so must be quite cosy) - though they all like perching out doors during the day  :roll:

I tried very hard to make them perch when they were little pullets, but they have never acquired the habit and I have stopped worrying about it. God knows why I ever thought it was worth worrying about. And we (erm OH) made them such a beautiful custom made hand finished perch.

Although they do not sleep in the nest box I still get filthy eggs as they all lay in the same spot and appear to trample any one else's eggs with muddy/pooey feet in an effort to get comfy. I will never undertand the henny thinking process.