No, I have not done this before, well not exactly. I did grow an Auto Ultimate in a 20 gallon SIP ( bottom fed pot ) a few years ago. Yes training will be a must I think! I think people place too much emphasis on the tap root, which on most Cannabis isn't all that long, it quickly tapers off after about 6" Most of your root mass spreads out. I've no idea what the potential size of this plant is, but we'll find out! I believe it is not known at this time what actually triggers flowering in autos. I do know she'll behave like an outdoor plant, she'll take a little longer to flower, It may have at least some relation to root mass.