All the math looks good, only problen is these engines burn vapor, not liquid, as the level in the tank goes down the surface area of the pool gets smaller and cannot vaporize enough gas fast enough to feed the unit under load. Likely as not you will need 2 1000 gallon tanks to keep up. Also if this is a Life Safety situation you do not have a prayer of getting a gas generator started and up to power in 3 seconds. Look into dual fuel units, they burn a combination of diesel and propane, they start quick on diesel and use propane to help lower the diesel consumption.
Life is tough, Life is tougher when you are stupid