Unless you're running a 12gram changer, why not keep the vertical reg on? It wouldn't make it that much bigger.
I run my converted autococker on CO2 and a 10oz tank and it works fine. It's a 2k3 with a Rat valve and STO vertical reg. The gun runs very low pressure and it's the best shooting gun I own.
If your glasses fog up and you want to make your own mask fans, here's how;
"My happiness doesn't depend on anything. My heart is always happy. I do have anger issues though."