Mags aren't air hogs if you use the proper length barrel sized for the paint you are using and have the proper level 10 spring for that barrel. You want as large a bottle as you can be comfortable with for woodsball. I use an 88ci tank when playing woodsball. I don't mind the size. An 80ci would probably be ideal. The regulator is the important part. It needs to be high pressure, approximately 850 to 900 psi, and have a high flow rate to handle the impulse needed to properly cycle a mag valve.
Except for the Automag in front, its usually the man behind the equipment that counts.