I have grown trees in tiny little net pots (less the 3 inch) the key is to be ready for the net pot to break. Basically, the roots are going to get big enough to split the little holes of the net pot. As long as the net pot is "trapped" it should be fine. I just zip tie the net pot to the bucket lid and it works fine for the entire grow.

I just finished a plant that produced 12 O's in a 2 inch net pot actually.

As for hieght, I grow SCROG only. Efficiency is through the roof and I never have to tie them up, plus it keeps plant numbers way down. Check it out. If you go the way you are thinking I really don't have much advice. I have trouble getting the size right for plants done that way. Too much difference from one plant to the next. I am sure someone will have a good idea though.

Good luck