I beat my ferrets to the punch with the whole "behind the door" toilet
stop.  I had a "boot tray" that is just a little bit wider and 2x as long
as the square ferret litter boxes they sell.  I had it as a tray under the
box to catch stray litter.  When I learned that Matthew was a rebel and
preferred to go near the box, he went on the tray, and not on my floor!  I
can open the door about =BE's and the box slides on the tray, while the
tray stays in the corner.
 
I've seen the trays at Home Depot this time on year.
 
The really good news is that since I was able to acquire wood stove pellets
this season, Matt is 100% in the litter box in the cage and in their room,
now if I could only stop him from going in FRONT of the box in the kitchen,
I would have three 100%-ers!  How lucky am I????  (Matt's just lucky that
he's the biggest, cuddliest ferret of the crew - you can't get mad!)
 
Kristeen, Katie, Matt & Al
[Posted in FML issue 2868]