If you are worried about antisyphoning a tank, and complications therewith, you could just use the tank vertically, I've done that with my mag, and most of my loaner guns, and it is the very most easiest way to keep guns from drinking liquid. You have to turn the gun upsidedown to suck liquid.
Buy up a few 9 oz tanks, and a bulk tank, and you are set for renegade.
I have two classic mags, both run CO2, and they work well. HPA is slightly better, but CO2 works pretty well.
I also concur with not getting aftermarket regulators for the valve, they just don't work as well as AGD ones.