I'm starting off with a 500 lbs old under ground propane tank to build my self a smoker. i plan on using primarily for doing pigs but would also like to to cook other stuff on it to. i think it would be cool to keep the center stack but I'm wondering if the will affect the air flow. 2nd I'm looking for ideas on what to do for a fire box. I've seen some use a 2nd but smaller tank along side or others build a square fire box on one end. what would be the advantage or disadvantage of both? anyone ever use a under ground tank before?