OK - I'm going to bump this.
I was at Target today, and I took a look at the Rubbermaid 66 quart tubs (I think those are probably the ones that Josh is using).
I will concede that the floor space is much smaller than I imagined it to be. And while the floor space is a little bigger than I would prefer for a baby, I will agree that it's probably workable if you can succesfully achieve and maintain proper heat and humidity.
The bulk of the size is taken up in height, rather than floor space.