Look at the 120gal build in my sig. That's a propane tank and it worked out perfect. just make sure you go through the necessary precautions b4 cutting into it.
1 - 100 lb. self-made cylinder grill/smoker
1 - 100 lb. self-made cylinder smoker
1 - 20 gal. self-made grill/smoker
1 - 25 gal. self-made vertical smoker
1 - 120 gal. self-made trailer stick-burner