You'd need a separate ESC and battery for each motor if you wanted to get a reasonable amount of power into the plane. I'll tell you, .40-size trainers are a bit underpowered on 10 cells. They fly okay and climb out well, but you don't have the same kind of power as with a .40 glow. 7 or 8 will be even worse.

Having each motor with its own battery and ESC will turn the plane into a 14-cell ship, which should perform fairly well.