Well, I'm a noob still and not much of an auto grower... but, I did just throw 2 freebie autos in with my last crop. They were both in #2 pots, which is technically less than 2 gallons. Anyway, I just wanted to let you know how big they got, and mind you these girls were started under 216w of T5 lighting, 24/7, for 5 weeks and then put into my flower tent with my photo-period girls under 600w HPS, 12/12, for the last 5 weeks. I know that isn't what autos like and my yield would suffer, I did my homework. But they were freebies and I thought I'd throw them in the back, see what happened. The Dinafem Cheese Auto went 10 weeks, got to be a bushy 24", and yielded 14.6 g dry. The Kannabia Mikromachine only went 9 weeks because it looked so pathetic at 39" weak inches of lankiness... Charlie Brown Xmas tree style. Sad... only yielded 9.6 g dry. But these were fairly neglected. Just did enough to keep them alive, and that ain't saying much. Mild version of Lucas formula with Floranova Bloom, medium was Pro-Mix HP.
You could probably do it if things were done right. Cheers and happy growing.