Hello Richard
Don't know how much space you have but a friend of mine bought a baby gate with the cat door opening and she puts the cat box behind it. She got hers at The Christmas Tree Shop for $30 I just seen one on amazon extra tall for $55

Chatanuga love the picture of the cat using the dog as a pillow
Do they ever get to visit each other?
The last pic looks like the kittens saying " whatcha got " TOO CUTE!