The hot (or cold if trying to cool with ice) water bottle is a doable thing if you have a a gas stove or gas water heater and few enclosures. Can't imagine trying that for a large collection during an extended power loss of a week or more. Glad you got a generator now Lynn; if a possibility, it's the way to go.
Agree with Lynn and do not recommend using a kerosene heater in an enclosed space due to possible carbon monoxide production. A portable gas (i.e. propane, natural gas, etc.) heater that is designed to be used inside and burn clean is a better choice.