Hello subnet_rx.....I think there may be some other things that you can do to still have success in bonsai.. One thing I know, and as Bill made reference to, keeping your trees in pots that are too deep will ruin the illusion of bonsai. They will loosley be bonsai and not really showable.. They will always look like a project in training or a patio plant...I think that instead of you bending to your situation, you should make the situation bend to you. I do not know what set up you have for your trees. However, there are things that are very simple to do. It may require a bit more efffort, but it can work.. You said you can water twice a day, morning and afternnon. Sometimes this is enough. Are you saying that you need to water 3 times a day?? You could just make some very simple things. Maybe even make a simple table looking thing with sheets of wood, metal screens and concrete blocks. When you go to work, just throw a tarp over it and put the trees underneath the bench. Actually, anything that you could attach a tarp to. Even if you tie it up with wire or twine and attach the ends to something would work.
In regards to root pruning in Fall. Althought it is done, in my opinion, it is always best to wait till Spring... Usually when trees are root pruned in Spring, it warms up shortly after so the tree can recover, so unless you can provide the tree with protection from the Winter, then root pruning in Fall may not be a good idea. I mean if you root prune a juniper in Fall, you probably would not want to subject it to freezing cold temeperatures, you would want to have it in a slightly heated environment. Which kind of interferes with the tree's natural cycle because it should be in the cold at this time. However, if you have a really mild winter, say it doesn't really get down much below 50, it might be ok.
I hope is helpful
Rob