I bonsai my mothers. It's not hard at all. Actually, it's not even real bonsai. It's just keeping your plants trimmed down to a manageable size for the pots you are keeping them in. Bonsai requires much more attention to detail. MJ is very forgiving and all but the most sensitive strains won't give you any guff about it.
I keep my mothers in 1 liter pots. I let them grow until they get about 14-18 inches tall and then trim them back to around 8-10 inches. If your plants are healthy, they will slow down for a couple days after and then get right back down to buisness. I find form isn't really too important when trimming. Just make them shorter. I don't bother with trimming roots either. I grow 2 runs a year and I just start extra clones and flower the mothers. That way I don't have root binding issues. You could trim roots if you want to, I have tried it, but I don't need to the way I grow.
One thing I might add is that if you want 16-20 cuts every 2-4 weeks, I would say you will need more mothers (if you go with a 1 lt pot) or you will need to go with a 3-4 lt pot to get in that range, in my opinion.
Here's a good thread that got me going in the right direction, if you are interested.
https://www.icmag.com/ic/showthread.php?t=31919&highlight=bonsai
