If you are going for max output then I'd roll with female photo seeds, 10gal bag (if you're doing soil), 1 plant. I've SCROG'd a 4x4 with 1 stem. Takes a lot of time but if you are looking for volume/yield, that's the way I'd go.
Topping autos? You have to know the strain or find someone that does. Do it too late and your yeild is going to suffer. Do it too early and your plant is going to stunt. They dont really give enough time to LSR/HST them properly as some of them finish so fast I'm just coming out of veg when they are flushing for harvest.
I love autos for outdoor. Absolutely love them. I have three going now that are well over 6ft tall. But I grew them single cola, naturally, so they look like Christmas trees lol :) The yeilds will be incredible good. But now that Ive grown them and understand how the plants from these 3 strains grow, I also know what kind of time I can safely spend in veg and know exactly the method that they will produce optimum flower. With all of three of these strains there is enough time to mainline for 8 colas without a problem.
Hope all of this makes sense.