Actually, that's somewhat false... I've been using CO2 setups for years (granted, running paintball guns, but hear me out). Paintball industry people have pretty much solved the horizontal tank problem. Yes, CO2 is stored as a liquid. However, some of that CO2 is also in the tank as a gas. When laying on it's side, yes, liquid CO2 will get into the regulator. HOWEVER, what many people are using is called an anti-siphon tube- it's an angled tube, that protrudes from the valve and is angled upward into the gaseous CO2. (It's professionally mounted so that it's UP all the time)Just a thought, maybe it could be adapted here.