What would you say are the most viable ways to upgrade from tri-box to quad-box or 5-box respectively?

For quad box it seems that I would have to sacrifice a free month of game time in order to allow my characters to level at the same speed.

For 5-box is there any better option than B-D and C-E? Would require a higher levelled (60+) toon on the main account to be joined with the others.