Another thought or two:
Since (presumably) the system will be inoperative for months at a time, you might consider a diesel system instead of gasoline-based. The diesel fuel will keep better than gas, is readily available and is safer to store.
Someone mentioned that their propane tanks floated away. Of course your gasoline or diesel containers would do the same thing. Store them higher than the generator. If they float away, you won't be able to use the generator anyway because it will be under water.
Noise from the generator:
You're only using it for extended periods of time during emergencies, right? Your neighbors should understand that there's an emergency under way. Maintenance operations will be of short duration and to keep peace with the neighbors, offer to consult with them on their own emergency plan.
If everyone in your neighborhood gets a generator, maybe you could set up regular maintenance dates/times so that everyone generates noise at the same time, rather than multiplying annoyances. Your neighbor's generator will be making so much noise that he won't hear yours.