OK, just got back from Petco armed with:
* a bundle of wood shavings for insulation
* a big fluffy pet bed
* treats
* food
* more treats
* litter
* a bunch of solid advice from an employee who's taking care of four semi-strays of her own
Plan A is to put our big old dog crate on the porch, fill it with insulation and the kitty bed, cover it with a warm blanket and a trash bag for waterproofing, and hope to Bast that Ceejay will accept it as outdoor shelter for the upcoming night of 28 degrees.
For the other five, Plan A is still All-Night Cat Party. I am NOT looking forward to chaperoning 5-6 kitties in a tiny cluttered apartment, but I'm looking forward to it a lot more than leaving the kids out in subfreezing weather.