If somebody wanted to set up a really nice breeder set up for a pair of Lace monitors, what would the minimum square footage of cage floorspace be in order to hope to successfully breed them in captivity?

I am thinking that the cage would have to be a minimum of 8' x 3' x 4' high. Is this even close? or should it be a lot bigger?

It would be fun to do a backyard enclosure, but I don't have the room,presently.