I also use the Tidy Cat clumping for multiple cats. And when I moved to Chicago 12 years ago (has it been that long?!!!?!) I lived in a very tiny studio apartment. There was literally only room for one litterbox, and T & P had no problem with it. Peanut would occassionally poop on a throw rug, but that was usually only when I was gone and was a sign of protest. I lived in small apartments for 6-7 years after that, and only had one litter box that entire time. Now I have 3 for 2 cats, but that's because I have the room and because Peanut has become much more...shall we say...particular?

I also see no problem with having a box in the loft if that is the only other place to put one. I really don't think cats care where the box is, as long as it's in a relatively quiet area where there's not a lot of traffic so they can do their business in peace - just like we like to do.

And the additional food and litter is really not a great expense when you have two compared to one, and I think Rizzo would be much happier which would definitely outweigh the extra cost because happy cat = healthy cat. Good luck in convincing your hubby. Unfortunately I have no advice whatsoever to offer in that department.