I reckon it could be done with the right strain under a 600 MH veg 10 weeks and 600 hps flower in a 4x4 with the right genetics, hydro and scrog.
The trouble is, if you're aiming to keep plant count down, you end up running 3 stages instead of 2. i.e. instead of having one in flower when the other is in clone/veg, you end up having one in clone/early veg, one in late veg and one in flower.