OMG, this cat situation is driving me insane!

What about using a metal dog crate, without a floor pan. He should be able to pee and sniff and see the world, but still be confined? They fold up rather easily and don't take up much space? We used one for my daughter's pet bunny, so he could go outdoors and graze grass, but still be safe from neighborhood dogs.

Or (and I'm not sure if they would be big enough) what about a ferret harness? The only creature rubberier than a cat, is a ferret.