I am in search of an appropriate covered cat litter box for my hens, which are of large breed (australorp, orpington, sussex). I can't seem to find a box that looks of the appropriate size. In particular the door openings just seem darn small. Are you guys cutting open the front? Please advise which one you have purchased that you think would be effective for a larger breed bird. I'm either not finding the right one or over thinking this whole thing. Not sure which! Thanks!